A radioactive element has a half life of 4 days. The fraction that has decayed in 16 days is?

A. (15)/16
B. (1)/16
C. (3)/4
D. (1)/4

Correct Answer:

Option A = (15)/16

Explanation

16 days = 4 half lives.
The fraction left 16 days = after 4 half live, =  (1/2)⁴ = (1)/16.
∴ fraction delayed = (15)/16