The radioisotpe, N-13,has a half-life of 10.0 minutes is used to image organs in the body. If an injected sample has an activity of 40 microcuries `(40,muCi)`, what is its activity after 25 minutes in the body?

Answer

7.07

Explanation

Activity, `A=A_(0)((1)/(2))^(t//t_(1//2))`
`:." "A=40mu Ci((1)/(2))^(25//10)" "implies" "A=(40)/(2^(5//2))mu Ci`
`A=(40)/((sqrt(2))^(5))=(40)/(4sqrt(2))=(10)/(sqrt(2))`
`A=5sqrt(2)mu CiimpliesA=7.07mu Ci`