An element with a mass of 740 grams decays by 28.4% per minute. To the nearest minute, how long will it be until there are 30 grams of the element remaining?

t=9.6 minutes

Step-by-step explanation:

Given

mass of element is

Decay rate

and we know

Amount of exponential decay is given by

Where

Substituting values we get

taking log both sides we get

x = ± 6i

step-by-step explanation:

x^2 = -36

take the square root of each side

sqrt(x^2) = sqrt(-36)

we know sqrt(ab) = sqrt(a) sqrt(b)

x = ±sqrt(36) sqrt(-1)

we know that sqrt (-1) = i

x = ± 6i