Question

average of 5 numbers is 57.8. the avaerage of he first and second numbers is 77.5. and the average of the forth and fifth is 46. what is the third number?

Answer 1

STEP 1: Find the sum of the 5 numbers

Average of 5 number = 57.8

Sum of the 5 numbers = 57.8 x 5 = 289

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STEP 2: Find the sum of the first 2 numbers:

Average of the 1st and 2nd number = 77.5

Sum of the 1st and 2nd number = 77.5 x 2 = 155

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STEP 3: Find the sum of the last 2 numbers:

Average of the 4th and 5th number = 46

Sum of the 4th and 5th number = 46 x 2 = 92

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STEP 4: Find the sum of the 4 numbers

Sum of the 1st, 2nd, 3rd and 4th number = 155 + 92 = 247

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STEP 5: Find the missing 3rd number:

Take away the sum of the 4 numbers from the sum of the 5 numbers will give us the missing missing number.

5th number = 289 - 247 = 42.

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Answer: The third number is 42.