Question:
Out of the five numbers average of first four numbers is 15 and the average of last four numbers is 12. Also last number is 18. What is the first number?
A48
B27
C33
D30
Answer:
D. 30
Explanation:
(a+b+c+d)/5 = 15 (b+c+d+e)/4 = 12 a+b+c+d = 15 × 4 = 60----------(1) b+c+d+e = 12 × 4 = 48----------(2) ----(1) - (2) a - e = 12 e = 18 a = 12 + 18 = 30
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