# In the Following Series Find 20th Number

9, 5, 1, -3, -7, -11, :

- -75
- -70
- -67
- -64

**Answer: (3) -67**

**Explanation:- **

**Formula-**

n^th term of the series = a + (n – 1)d

n^th term of the series = a + (n – 1)d

**Where, a = first firm and d = difference between two terms.**

Series :- 9, 5, 1, -3, -7, -11, ……….

a = 9 and d = 1 – 5 = – 4

Then, 20th number = 9 + (20 – 1) (-4)

= 9 + 19 (-4)

= 9 – 76

= – 67

Then, the 20th number of the given series is -67.

Hence, the answer is (3) -67.