To model half-life, use the formula

. Here,

is the amount remaining after a length of time

.

is the amount that you start with.

is the half-life. You plug in 50 for

, 10 for

, and 25 for

. You get

.
Answer:
The swimming pool is 5 times bigger.
Step-by-step explanation:
5 x 3.14=15.7 ft
15 x 2 x 3.14= 78.5 ft
78.5/15.7=5 times bigger
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