An exponent is a small number written on the upper right of another number which is called the base. It denotes the number of times the base to be multiplied by itself. What is the value of -52?

a.

-10

b.

10

c.

25

d.

-25

If the population of a certain country increases at the rate of one person every 15 seconds, by how many persons does the population increase in 20 minutes?

a.

100

b.

240

c.

80

d.

150