RRB NTPC Mains or Stage 2 Model Paper 10 with solutions

Question : 12 of 120

Marks: +1, -0

The average of four consecutive numbers A, B, C and D respectively is 56.5. What is the product of A and C?

Solution:

(d) Let four consecutive numbers are

A = (x), B = (x +1), C = (x + 2) and D = (x +3)

According to question
Average=

{( x)+ ( x+1)+ (x+ 2)+ (x+ 3)}/ 4

⇒ 56.5= {4 x+6} /4

⇒ 226 = 4x + 6

⇒ 4x = 226 - 6 = 220

∴ 220

x=220/4= 55

∴ Product of A and C

= (x)×(x + 2) = (55) ×(55 + 2) = 55×57 = 3135

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