Progression | Jamb Mathematics
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Cadet, listen up! Your next mission is to master the art of
progression—arithmetic, geometric, and
beyond—because precision and strategy are key to victory. Drill through formulas, decode patterns, and sharpen
your problem-solving skills, because only the well-prepared survive the battlefield of mathematics.
Fall in
and get to work! 🚀🔥
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Are you preparing for your JAMB Mathematics exam and feeling a bit uncertain about how to approach the topic
of
Progression? Don’t worry—you’re in the right place! This lesson is here to break it down in a simple,
clear, and engaging way, helping you build the strong foundation you need to succeed. Whether you're
struggling with complex questions or just seeking a quick refresher, this guide will boost your understanding
and confidence. Let’s tackle
Progression together and move one step closer to achieving your exam success!
Blissful learning.
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Calculation problem involving arithmetic progression
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1. Find the 10th term of the AP: 2, 5, 8, 11, ...
Solution:
The formula for the nth term of an AP is:
an=a+(n−1)d
Where:
- a=2 (first term),
- d=5−2=3 (common difference),
- n=10.
a10=2+(10−1)⋅3
=2+9⋅3
=2+27=29
2. Find the sum of the first 15 terms of the AP: 3, 7, 11, 15, ...
Solution:
Sum of the first
n terms of an AP is given by:
Sn=2n(2a+(n−1)d)
Here,
- a=3,
- d=7−3=4,
- n=15.
S15=215(2⋅3+(15−1)⋅4)
=215(6+56)
=215⋅62
=15⋅31
3. The 7th term of an AP is 20, and the 13th term is 50. Find the first term and common difference.
Solution:
Using the formula:
an=a+(n−1)d
For
a7=20:
a+6d=20
For
a13=50:
a+12d=50
Subtracting equations:
(a+12d)−(a+6d)=50−20
Substituting
d in
a+6(5)=20:
a+30=20
Answer: a=−10,
d=5
4. Find the number of terms in the AP: 4, 10, 16, ..., 88.
Solution:
Using
an=a+(n−1)d,
- a=4,
- d=10−4=6,
- an=88.
88=4+(n−1)6
88−4=(n−1)6
84=(n−1)6
5. The sum of the first 20 terms of an AP is 1000. The first term is 7. Find the common difference.
Solution:
Using
Sn=2n(2a+(n−1)d),
1000=220(2⋅7+(20−1)d)
1000=10(14+19d)
100=14+19d
d=1986=4.526
Answer: d=4.526
6. Find the 12th term of the AP: 6, 13, 20, 27, ...
Solution:
Using
an=a+(n−1)d,
- a=6,
- d=13−6=7,
- n=12.
a12=6+(12−1)⋅7
=6+11⋅7
=6+77=83
7. Find the sum of the first 25 terms of the AP: 2, 8, 14, 20, ...
Solution:
Using
Sn=2n(2a+(n−1)d),
- a=2,
- d=8−2=6,
- n=25.
S25=225(2⋅2+(25−1)⋅6)
=225(4+144)
=225⋅148
=25⋅74
8. Find the number of terms in the AP: 3, 7, 11, ..., 87.
Solution:
Using
an=a+(n−1)d,
- a=3,
- d=7−3=4,
- an=87.
87=3+(n−1)4
87−3=(n−1)4
84=(n−1)4
9. The 8th term of an AP is 36, and the 16th term is 84. Find the first term and common difference.
Solution:
Using
an=a+(n−1)d,
For
a8=36:
a+7d=36
For
a16=84:
a+15d=84
Subtracting equations:
(a+15d)−(a+7d)=84−36
Substituting
d in
a+7(6)=36:
a+42=36
Answer: a=−6,
d=6
10. The sum of the first 30 terms of an AP is 2400. The first term is 10. Find the common difference.
Solution:
Using
Sn=2n(2a+(n−1)d),
2400=230(2⋅10+(30−1)d)
2400=15(20+29d)
160=20+29d
d=29140=4.83
Answer: d=4.83
11. Find the 20th term of the AP: 50, 45, 40, 35, ...
Solution:
Using
an=a+(n−1)d,
- a=50,
- d=45−50=−5,
- n=20.
a20=50+(20−1)(−5)
12. Find the sum of the first 12 terms of the AP: 5, 10, 15, ...
Solution:
Using
Sn=2n(2a+(n−1)d),
- a=5,
- d=5,
- n=12.
S12=212(2⋅5+(12−1)5)
=6(10+55)
Here are the remaining 13 unique arithmetic progression (AP) problems with step-by-step solutions.
13. The 5th term of an AP is 25, and the 10th term is 50. Find the first term and common difference.
Solution:
Using
an=a+(n−1)d,
For
a5=25:
a+4d=25
For
a10=50:
a+9d=50
Subtracting equations:
(a+9d)−(a+4d)=50−25
Substituting
d in
a+4(5)=25:
a+20=25
Answer: a=5,
d=5
14. Find the number of terms in the AP: 7, 14, 21, ..., 133.
Solution:
Using
an=a+(n−1)d,
- a=7,
- d=14−7=7,
- an=133.
133=7+(n−1)7
133−7=(n−1)7
126=(n−1)7
15. The sum of the first 40 terms of an AP is 8200. The first term is 15. Find the common difference.
Solution:
Using
Sn=2n(2a+(n−1)d),
8200=240(2⋅15+(40−1)d)
8200=20(30+39d)
410=30+39d
d=39380=9.74
Answer: d=9.74
16. Find the 25th term of the AP: 1, 4, 7, 10, ...
Solution:
Using
an=a+(n−1)d,
- a=1,
- d=3,
- n=25.
a25=1+(25−1)3
17. Find the sum of the first 18 terms of the AP: 10, 20, 30, ...
Solution:
Using
Sn=2n(2a+(n−1)d),
- a=10,
- d=10,
- n=18.
S18=218(2⋅10+(18−1)10)
=9(20+170)
=9⋅190
18. The first term of an AP is -3, and the 21st term is 57. Find the common difference.
Solution:
Using
an=a+(n−1)d,
57=−3+(21−1)d
57+3=20d
d=2060=3
19. The sum of the first 50 terms of an AP is 5050. Find the first term if the common difference is 2.
Solution:
Using
Sn=2n(2a+(n−1)d),
5050=250(2a+(50−1)2)
5050=25(2a+98)
202=2a+98
20. Find the 15th term of the AP: 100, 97, 94, ...
Solution:
Using
an=a+(n−1)d,
- a=100,
- d=97−100=−3,
- n=15.
a15=100+(15−1)(−3)
21. Find the number of terms in the AP: 50, 45, 40, ..., 5.
Solution:
Using
an=a+(n−1)d,
- a=50,
- d=−5,
- an=5.
5=50+(n−1)(−5)
5−50=(n−1)(−5)
−45=(n−1)(−5)
22. The 6th term of an AP is 19, and the 11th term is 34. Find the first term and common difference.
Solution:
Using
an=a+(n−1)d,
For
a6=19:
a+5d=19
For
a11=34:
a+10d=34
Subtracting equations:
(a+10d)−(a+5d)=34−19
Substituting
d in
a+5(3)=19:
a+15=19
Answer: a=4,
d=3
23. Find the sum of the first 22 terms of the AP: 8, 14, 20, ...
Solution:
Using
Sn=2n(2a+(n−1)d),
- a=8,
- d=6,
- n=22.
S22=222(2⋅8+(22−1)6)
=11(16+126)
=11⋅142
24. The sum of the first 60 terms of an AP is 18300. Find the first term if the common difference is 5.
Solution:
Using
Sn=2n(2a+(n−1)d),
18300=260(2a+(60−1)5)
18300=30(2a+295)
610=2a+295
Answer: a=157.5
25. Find the 30th term of the AP: -5, -2, 1, ...
Solution:
Using
an=a+(n−1)d,
- a=−5,
- d=3,
- n=30.
a30=−5+(30−1)3
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Calculation problems involving geometric progression
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1. Find the 10th term of the GP: 3, 6, 12, 24, ...
Solution:
The formula for the nth term of a GP is:
an=ar(n−1)
Where:
- a=3 (first term),
- r=36=2 (common ratio),
- n=10.
a10=3×2(10−1)
=3×512
2. Find the sum of the first 6 terms of the GP: 5, 10, 20, 40, ...
Solution:
The sum of the first
n terms of a GP is given by:
Sn=r−1a(rn−1),for r=1
Here,
- a=5,
- r=2,
- n=6.
S6=2−15(26−1)
=5(64−1)
3. The 4th term of a GP is 48, and the 7th term is 384. Find the first term and common ratio.
Solution:
Using
an=ar(n−1),
For
a4=48:
ar3=48
For
a7=384:
ar6=384
Dividing both equations:
ar3ar6=48384
Substituting in
ar3=48:
a(23)=48
Answer: a=6,
r=2
4. Find the sum to infinity of the GP: 20, 10, 5, 2.5, ...
Solution:
The sum to infinity of a GP is:
S∞=1−ra,for ∣r∣<1
Here,
- a=20,
- r=2010=0.5.
S∞=1−0.520
=0.520
5. Find the number of terms in the GP: 4, 12, 36, ..., 2916.
Solution:
Using
an=ar(n−1),
- a=4,
- r=412=3,
- an=2916.
2916=4×3(n−1)
Dividing by 4:
42916=3(n−1)
729=3(n−1)
Since
729=36,
6. Find the 8th term of the GP: 2, 6, 18, 54, ...
Solution:
Using the formula:
an=ar(n−1)
Where:
- a=2,
- r=26=3,
- n=8.
a8=2×3(8−1)
=2×2187
7. Find the sum of the first 5 terms of the GP: 1, 4, 16, 64, ...
Solution:
Sn=r−1a(rn−1)
- a=1,
- r=4,
- n=5.
S5=4−11(45−1)
=31024−1
=31023=341
8. The 6th term of a GP is 81, and the 10th term is 6561. Find the common ratio.
Solution:
a6=ar5=81
a10=ar9=6561
Dividing both:
ar5ar9=816561
9. Find the sum to infinity of the GP: 8, 4, 2, 1, ...
Solution:
S∞=1−ra
- a=8,
- r=84=0.5.
S∞=1−0.58
=0.58=16
10. Find the number of terms in the GP: 3, 9, 27, ..., 2187.
Solution:
2187=3×3(n−1)
32187=3(n−1)
729=3(n−1)
11. The sum of the first 7 terms of a GP is 5461. The first term is 1, and the common ratio is 2. Find S7.
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Solution:
S7=2−11(27−1)
12. Find the 15th term of the GP: 5, 10, 20, ...
Solution:
a15=5×2(15−1)
=5×214
=5×16384
13. The 9th term of a GP is 512, and the 3rd term is 8. Find the common ratio.
Solution:
ar2ar8=8512
14. Find the sum to infinity of the GP: 6, 2, 32,...
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Solution:
S∞=1−ra
- a=6,
- r=62=31.
S∞=1−316
=326
=6×23
15. The sum of the first 8 terms of a GP is 765. The first term is 3, and the common ratio is 2. Find S8.
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Solution:
S8=2−13(28−1)
=3(256−1)
=3×255
16. Find the number of terms in the GP: 7, 14, 28, ..., 1792.
Solution:
1792=7×2(n−1)
71792=2(n−1)
256=2(n−1)
17. Find the sum to infinity of the GP: 12, 4, 34,..
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Solution:
S∞=1−ra
- a=12,
- r=124=31.
S∞=1−3112
=3212
=12×23
18. The sum of the first 10 terms of a GP is 3072. The first term is 1, and the common ratio is 2. Find S10.
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Solution:
S10=2−11(210−1)
19. Find the 20th term of the GP: 10, 5, 2.5, ...
Solution:
a20=10×0.5(20−1)
=10×0.519
=10×5242881
=52428810
Answer: 52428810
20. Find the sum of the first 12 terms of the GP: 1, -1, 1, -1, ...
Solution:
Since
r=−1, the sum alternates.
S12=−1−11((−1)12−1)
=−2(1−1)
Calculation problem involving sum of the nth term of a geometric progression
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1. Find the sum of the first 7 terms of the GP: 2, 6, 18, 54, ...
Solution:
The sum of the first
n terms of a GP is given by:
Sn=r−1a(rn−1),for r=1
Here:
- a=2,
- r=26=3,
- n=7.
S7=3−12(37−1)
=22(2187−1)
=2(1093)
2. Find the sum of the first 6 terms of the GP: 4, -12, 36, -108, ...
Solution:
Using:
Sn=r−1a(rn−1)
Here:
- a=4,
- r=−3,
- n=6.
S6=−3−14((−3)6−1)
=−44(729−1)
=−44(728)
3. The sum of the first 8 terms of a GP is 3280. The first term is 5, and the common ratio is 2. Find S8.
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Solution:
Using:
Sn=r−1a(rn−1)
- a=5,
- r=2,
- n=8.
S8=2−15(28−1)
=5(256−1)
4. Find the sum of the first 10 terms of the GP: 1, 3, 9, ...
Solution:
Using:
Sn=r−1a(rn−1)
- a=1,
- r=3,
- n=10.
S10=3−11(310−1)
=2310−1
=259049−1
=259048
5. Find the sum of the first 9 terms of the GP: 7, 21, 63, ...
Solution:
Using:
Sn=r−1a(rn−1)
- a=7,
- r=3,
- n=9.
S9=3−17(39−1)
=27(19683−1)
=27(19682)
6. The sum of the first 5 terms of a GP is 242. The first term is 2, and the common ratio is 3. Find S5.
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Solution:
Using:
Sn=r−1a(rn−1)
- a=2,
- r=3,
- n=5.
S5=3−12(35−1)
=22(243−1)
7. Find the sum of the first 7 terms of the GP: 5, 10, 20, 40, ...
Solution:
Using:
Sn=r−1a(rn−1)
- a=5,
- r=2,
- n=7.
S7=2−15(27−1)
=5(128−1)
8. Find the sum of the first 12 terms of the GP: 3, 6, 12, ...
Solution:
Using:
Sn=r−1a(rn−1)
- a=3,
- r=2,
- n=12.
S12=2−13(212−1)
=3(4096−1)
=3(4095)
9. Find the sum of the first 6 terms of the GP: 10, -20, 40, -80, ...
Solution:
Using:
Sn=r−1a(rn−1)
- a=10,
- r=−2,
- n=6.
S6=−2−110((−2)6−1)
=−310(64−1)
=−310(63)
10. The sum of the first 4 terms of a GP is 1875. The first term is 5, and the common ratio is 5. Find S4.
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Solution:
Using:
Sn=r−1a(rn−1)
- a=5,
- r=5,
- n=4.
S4=5−15(54−1)
=45(625−1)
=45(624)
=43120
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Thank you for taking the time to read my blog post! Your interest and engagement mean so much to me, and I hope
the content provided valuable insights and sparked your curiosity. Your journey as a student is inspiring, and
it’s my goal to contribute to your growth and success.
paragraph
If you found the post helpful, feel free to share it with
others who might benefit. I’d also love to hear your thoughts, feedback, or questions—your input makes this
space even better. Keep striving, learning, and achieving! 😊📚✨
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I recommend you check my Post on the following:
paragraph
Thank you for taking the time to read my blog post! Your interest and engagement mean so much to me, and I hope
the content provided valuable insights and sparked your curiosity. Your journey as a student is inspiring, and
it’s my goal to contribute to your growth and success.
paragraph
If you found the post helpful, feel free to share it with
others who might benefit. I’d also love to hear your thoughts, feedback, or questions—your input makes this
space even better. Keep striving, learning, and achieving! 😊📚✨
paragraph
I recommend you check my Post on the following: