## Sequence and Series Questions and Answers Part-3

1. 0.7, 2.8, 11.2, 44.8, ?
a) 178.2
b) 177.2
c) 179
d) 179.2

Explanation: GP with common ratio 4. Hence, the next term would be 179.2 i.e., option (d).

2. 1, 5/4, 21/16, ______ what will be the nth term of the series?
a) $\left\{1-\left(1/4\right)^{n}\right\}/\left(3/4\right)$
b) $\left\{1+\left(1/3\right)^{n}\right\}/\left(2/3\right)^{n}$
c) $\left\{\left(1/3\right)^{n}+1\right\}/\left(2/3\right)$
d) none of these

Explanation: The formula for the nth term can be easily verified from the given terms of the series. Option (a) is correct.

3. 600, 550, 450, 300, ?
a) 50
b) 0
c) 100
d) 150

Explanation: The series follows the logic of –50, –100, –150 and hence the next term of the series should be 300 – 200 = 100. Correct answer is option (c)

4. 1, 2, 3, 6, 11, 20, 37, 68 ?
a) 125
b) 126
c) 124
d) 105

Explanation: Beginning with 6, each term of the series is the sum of the previous 3 terms. Hence, the next term would be 125. So, the answer is option (a).

5. 12, 24, 36, 48, ?, 72
a) 50
b) 55
c) 60
d) 70

Explanation: AP with common difference 12. Hence, the unknown term is 12. So option (c) is the answer.

6. 1, 6, 11, ______ what will be its 15th term?
a) 46
b) 76
c) 66
d) 71

Explanation: AP with common difference 5. Hence, 15th term is 71. Answer is option (d)

7. –3, 4, 23, 60, 121?
a) 22
b) 212
c) 205
d) none of these

Explanation: +7, +19, +37, +61. Hence, the next term in the series would be 121 + 91 = 212, answer is (b).

8. 20, 26, 62, ?, 1574
a) 125
b) 150
c) 278
d) 200

Explanation: We are consecutively adding increasing powers of 6. Hence, option (c) is correct.

9. 45, 40, 35, _____ which term will be the first negative term of the series?
a) $10^{th}$ term
b) $11^{th}$ term
c) $12^{th}$ term
d) $13^{th}$ term