Question

Why is the answer 20 for number 38?

Answer 1

Given:

production of electricity in Minnesota in 10^9 kWh

in 2009 = 12 (renewable) = 15% of total production (P)

in 2015 = 25% (renewable) of total production (P)

Total production of the two years are the same.

Solution:

First find P

we know that 12 * 10^9 kWh is 15% of P, or

0.15P=12*10^9

=> P=12*10^9/0.15 = 80*10^9 kWh

For 2015,

25% of P is renewable, therefore

x=0.25P=0.25*80*10^9 kWh = 20 * 10^9 kWh

Hence answer is 20, in units of 10^9 kWh.