The Total solution for NCERT class 6-12
Which term of the progression 0.004, 0.02, 0.1, …. is 12.5?
By using the formula,
Tn =arn-1
Given:
a = 0.004
r = t2/t1 =(0.02/0.004)
= 5
Tn =12.5
n = ?
So, Tn =arn-1
12.5 = (0.004) (5)n-1
12.5/0.004 = 5n-1
3000 = 5n-1
55 = 5n-1
5 = n-1
n = 5 + 1
= 6
∴ 6th termof the progression 0.004, 0.02, 0.1, …. is 12.5.