Question

11 the table below shows the radioactivity level of a substance after the given time, t, in seconds.

time (seconds)	radioactivity level
1	10
2	5
3	2.5
4	1.25

what is the average rate of change in radioactivity level over the interval ( 1 leq t leq 3 )?
(1) 3.75
(3) 4.6875
(2) ( -3.75 )
(4) ( -4.6875 )

Explanation:

Step1: Identify values at t=1 and t=3

At t=1: 10; at t=3: 2.5

Step2: Calculate average rate of change

Formula: $\frac{\text{Change in radioactivity}}{\text{Change in time}} = \frac{2.5 - 10}{3 - 1} = \frac{-7.5}{2} = -3.75$

Answer:

(2) -3.75