Cobalt 60 has an annual decay rate of 13% how many grams of a 300 g sample one will remain after 20 years round the answer to two decimal places

18.51 grams.

Step-by-step explanation:

We have been given the decay rate

We have general equation for decay which is:

;

Here, we are given with initial sample which is a=300

b=1-13%

And t is 20 years.

We will subatitute the values in the formula we get:

After simplification we get y=18.51 grams.

The sample remain will be 18.51 grams.

d 25 pi/6

step-by-step explanation:

the diameter is 10 inches

the radius is 1/2 of the diameter or 5 inches

the area of the circle is

a = pi r^2

  = pi 5^2

  = 25 pi

the slice is 60 degrees of the entire circle.

60 degrees out of 360   60/360 = 1/6

the area of the slice is 1/6 of the circle

a slice = 1/6 a circle

a slice = 1/6 * 25 pi