Question 54

The average of a,b,c is 20 and that of b,c,d is 25; if d=30, then the value of a is

Solution

Average of a,b,c = 20

=> Sum = $$a+b+c=3\times20=60$$ ----------(i)

Similarly, sum of b,c,d = $$b+c+d=3\times25=75$$ -----------(ii)

Also, $$d=30$$

Substituting it in equation (ii)

=> $$b+c=75-30=45$$

Again substituting above value in equation (i), we get :

=> $$a+45=60$$

=> $$a=60-45=15$$

=> Ans - (D)

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