For the given five values 10, a, 13, b, 25, the 3-years moving averages are 15, 18, 19. The value of a+b is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 41
Each 3-year moving average is the mean of three consecutive values. The first one gives a:
\( \displaystyle \frac{10+a+13}{3}=15 \)
\( a+23=45 \)
\( a=22 \)
The second one gives b:
\( \displaystyle \frac{22+13+b}{3}=18 \)
\( 35+b=54 \)
\( b=19 \)
Check: the third average is (13 + 19 + 25)/3 = 19, as given.
\( a+b=22+19=41 \)