6. Lucy is trying to save water. She has reduced the time she spends in her shower by one quarter. Also, she has lowered the water pressure to reduce the rate the water comes out of the shower head by a quarter. By what fraction has Lucy reduced the total amount of water she uses when she showers?
A $\frac{3}{8}$
B $\frac{1}{16}$
C $\frac{5}{12}$
D $\frac{7}{16}$
E $\frac{9}{16}$
SOLUTION
D

In total Lucy uses $\frac{3}{4} \times \frac{3}{4}=\frac{9}{16}$ of the water volume that she used before. So she has reduced the total amount of water by $\frac{7}{16}$.