There was a sample of 700 milligrams of a radioactive substance to start a study. since then, the sample has decayed by 3.1% each year. let t be the number of years since the start of the study. let y be the mass of the sample in milligrams.

write an exponential function showing the relationship between
and y and t
.

y = 700 (0.969)^t

Step-by-step explanation:

Using the depreciation formula after a given period of time.

A = P (1- r/100)^n

Where, A is the initial value

P is the original value

r is the rate of depreciation and

n is the time taken in years

Therefore;

A will be the new mass of the sample after decay,y

P is the original mass of the sample before decay, 700 mg

r is the rate of decay each year, 3.1% and

n is the number of years, t

Hence;

y = 700 (1- 3.1/100)^t

y = 700 (96.9/100)^t

y = 100(0.969)^t

126.66 m²

step-by-step explanation:

the pertinent area formula is a = πr², where r is the radius.

here, a = π(6.35 m)² = 40.32π, or approximately 126.66 m²

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step-by-step explanation: