Question 10

The average of 6 consecutive integers is 15/2. What is the average of last three integers?

Solution

Let the 6 consecutive integers be = $$(x),$$ $$(x+1),$$ $$(x+2),$$ $$(x+3),$$ $$(x+4)$$ and $$(x+5)$$

Sum of integers = $$(x)+$$ $$(x+1)+$$ $$(x+2)+$$ $$(x+3)+$$ $$(x+4)+$$ $$(x+5)$$ $$=\frac{15}{2}\times6$$

=> $$6x+15=45$$

=> $$6x=45-15=30$$

=> $$x=\frac{30}{6}=5$$

$$\therefore$$ Average of last three integers = $$\frac{(5+3)+(5+4)+(5+5)}{3}$$

= $$\frac{27}{3}=9$$

=> Ans - (B)

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