Consider the following data and then calculate the half-life for this particular isotope: Time Activity (cpm)
0 days 320,000
40 days 216,100
100 days 120,000
(A) 35.2 days.
(B) 75.6 days.
(C) 70.6 days.
(D) 62.9 days.
(E) None of these.

D. 62.9 days

Explanation:

Half Life Cpm activity:

320,000 / 2 = 160,000

At 100 days cpm is 120,000 then cpm 160,000 will be at 62.9 days.

[320,000 - 216,100] / 40 days = 2,597.5

160,000 / 2,597.5 = 62.9 days.

the investment was $14,174.196

explanation:

a lump sum means that the father of the example made one deposit and leave it be.

we need to know the value of a capital that generated at 4.05% per year during 28 years the sum of $48,613.24

now clearing the formula to solve for capital we got:

and we reach the answer investment = $14,174.20

answerconversion factor;