Write an exponential decay model for each situation. The value of x for each value of f(x) will lie between two consecutive whole numbers. List the whole
numbers.

4. initial value: 1,000
decay rate: 20%
f(x) = 500

5. initial value: 1,800
decay rate: 7%
f(x) = 400

6. initial value: 1,200
decay rate: 12.5%
f(x) = 450

Ahigh-altitude spherical weather balloon expands as it rises, due to the drop in atmospheric pressure. suppose that the radius r increases at the rate of 0.02 inches per second, and that r = 36 inches at time t = 0. determine the equation that models the volume v of the balloon at time t, and find the volume when t = 360 seconds. v(t) = 4π(0.02t)2; 651.44 in3 v(t) = 4π(36 + 0.02t)2; 1,694,397.14 in3 v(t) = four pi times the product of zero point zero two and t to the third power divided by three.; 4,690.37 in3 v(t) = four pi times the quantity of thirty six plus zero point zero two t to the third power divided by three.; 337,706.83 in3