Question 10

The average of 7 numbers is 30. If the average of first three numbers is 25 and that of last three numbers is 35, then what is the fourth number?

Solution

Average of 7 numbers = 30

=> Sum of the numbers = $$30\times7=210$$

Now, sum of first 3 numbers = $$25\times3=75$$

Similarly, sum of last 3 numbers = $$35\times3=105$$

=> Fourth number = $$210-(75+105)=210-180=30$$

=> Ans - (A)

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