1.

Among 5 numbers, first number is double of second number and three-fourth of third number. The average of 5 numbers is 55. If the sum of remaining two numbers is 88, find the value of 3rd number.1. 882. 603. 774. 66

Answer» Correct Answer - Option 1 : 88

Given:

The average of 5 numbers is 55.

The first number is double of the second number and three-fourth of the third number.

The sum of fourth and fifth number = 88.

Concepts used:

Average = (Sum of all observations)/(Number of observations)

Calculations:

Let the first number, second number, third number, fourth number, fifth number be a, b, c, d and e respectively.

Sum of all observations = 55 × 5 = 275

⇒ a + b + c + d + e = 275      ----(1)     

First number is double of the second number. 

⇒ a = 2b

⇒ b = a/2    

First number is 3/4th of third number.

⇒ a = 3c/4

⇒ c = 4a/3   

The sum of remaining two numbers is 88.

⇒ d + e = 88    

Putting the value of b, c, d and e in eq (1),

⇒ a + b + c + d + e = 275 

⇒ a + a/2 + 4a/3 + 88 = 275

⇒ 17a/6 = 275 - 88

⇒ 17a/6 = 187

⇒ a = 187 × 6/17 = 66

The third number = c = 4a/3 = 4 × 66/3 = 88

∴ The value of third number is 88.


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