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There are eight numbers, and their average is 7.5. It is known that the average of the first five numbers is 8.8, and the average of the last four numbers is 9.5. What is the fifth number?
The sum of 8 numbers = 8 × 7.5 = 60
The sum of the first five numbers = 5 × 8.8 = 44;
The sum of the last four numbers = 4 × 9.5 = 38;
Use the first 8 numbers - the first 5 numbers = 60-44 = 16 (is the sum of the last 3 numbers)
Use the sum of the last four numbers - the last three numbers = 38-16 = 22
So the fifth number is 22
There are eight numbers. Their average is 7.5. We know that the average of the first five numbers is 8.8, and the average of the last four numbers is 9.5. What is the fifth number?
The average number of eight numbers is 7.5, so the sum of the eight numbers is 7.5 * 8 = 60. Similarly, the sum of the first five numbers is 8.8 * 5 = 44, the sum of the last four numbers is 9.5 * 4 = 38, and the sum of the first five numbers and the last four numbers is 44 + 38 = 82. The fifth number is added one more time than the sum of the eight numbers, so the five numbers at the department level are 82-60 = 22
There are eight numbers, the average of which is known to be 9.2, the average of the first four numbers is 8.9, and the average of the last five numbers is 9.5. What is the fourth number?
The fourth number: (8.9 × 4 + 9.5 × 5) - 9.2 × 8 = 9.5
The average of the eight numbers is 7.5. It is known that the average of the first five numbers is 8.8, and the average of the last four numbers is 9.5. What is the fifth number?
8.8×5+9.5×4-7.5×8
=44+38-60
=82-60
=22
A: the fifth number is 22
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The average of the eight numbers is 7.5, the average of the first five numbers is 8.8, the average of the last four numbers is 9.5, and the fifth number is?
Determinant
8.8*5+9.5*4-7.5*8=22
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