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2 years ago

The mean of four numbers is 70. When a fifth number is included, the mean of the five numbers is 80. What is the fifth number?

Mathematics

1 answer:

Yakvenalex [24]2 years ago

3 0

<h3>Answer: 120</h3>

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Explanation:

S = sum of the first four values

S/4 = 70 since we divide the sum by 4 to get the mean of the first four values

S = 280 is the result after multiplying both sides by 4

Let x be the fifth unknown value. Adding it onto S leads to S+x = 280+x. This represents the sum of all five values.

Dividing that sum 280+x over 5 leads to the new mean 80, which leads to...

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(280+x)/5 = 80

280+x = 5*80

x+280 = 400

x = 400-280

x = 120

The fifth number is 120

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2 years ago

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2 years ago

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2 years ago

10. A square is shown below. If the perimeter of the square is 97 inches, what is the value of x?

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3 years ago

A class of 40 students elected a class president. There were 12 votes for Candidate A, and 18 votes for Candidate B.

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Hey there, Bulgogi!

The correct answer will be the first one since [I'm assuming] you know that to calculate the percentage of something, it's the amount of that something divided by the total amount but since only 30 students voted [12+18] multiplied by 100.

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3 years ago