If a certain toy store's revenue in November was 4/5 of its revenue in December and its revenue in January was 3/4 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?
Choose the correct answer
A) 1/4
B) 1/2
C) 2/3
D) 2
E) 4
Let 2ec rev =100   Then Nov rev is 4/5 (100) =&gt; 80   Therefore Jan rev = 3/4(Nov rev) = 3/4(80) =&gt; 60   Hence 2ec rev = x*( Nov rev+Jan rev)/2   100 = x* (80+60)/2   x = 100/70 =&gt; 1.42=2   Ans) 2
<result>D</result>
If a certain toy store's revenue in November was 4/5 of its revenue in December and its revenue in January was 3/4 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?