The half-life of a substance is the amount of time it takes for half of the amount of substance to decay. The half-life of a pesticide is 2 years. Initially there are 500 grams of pesticide. How much pesticide is left after 10 years? Round to the nearest hundredth.

15.625 grams

Step-by-step explanation:

The decay is First order reaction

The half life of the first order reaction is given by

T(1/2)  = ㏑2/K

where K is the reaction constant for the first order reaction

T(1/2) = 2

2 = ln 2 /K

K = ln2/2

The equation of the first order reaction is given by

Kt = ln ()

where

t = time = 10years

Ro = initial concentration

R = amount left after time t

upon substituting the values

5ln2 = ln (500/R)

ln = ln (500/R)          (a*lnb = ln)

R = 500/32  = 15.625grams

Therefore the amount of pesticide left after 10 years is 15.625grams

walter needs to make at least 5 more cookies but no more than 40. 5 ≥ x ≥ 40;

step-by-step explanation:

walter has to make a minimum of 20 cookies. he already has 15 cookies made, so he must make 5 more to meet the minimum.

the maximum amount of cookies he can make is 55. he already has 15, so he has to make no more than 40 more cookies to meet the maximum.

the answer will be