# How do you find the 10th term in the geometric sequence 320, 160, 80, 40, ...?

##### 1 Answer

Geometric progression

#### Explanation:

320 , 160 , 80 , 40 , .....

First of all, you've to find the first term of the sequence,a,

first term, a =320

Then, you've to find the common ratio of the sequence.So,divide the second term with the first term,

common ratio, r = 160/320

```
r = 1/2
```

Use the formula

#T_10 = 320[(1/2)^(9)]#

#T_10 = 5/8#