The average of the sales of an electronics shop in the years 1991, 1992, 1993, and 1994 is 2000, and that for the years 1992, 1993, 1994, and 1995 is 2200. If the sales in 1995 are 1800, find the sales in 1991.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 1000.
Total sales in years (1991 + 1992 + 1993 + 1994) = 4 × 2000 = 8000........(1)
Total sales in years (1992 + 1993 + 1994 + 1995) = 4 × 2200 = 8800........(2)
Subtracting equation 1 from 2
⇒ year 1995 - year 1991 = 8800 - 8000
⇒ year 1995 - year 1991 = 800
⇒ 1800 - year 1991 = 800
⇒ year 1991 = 1000