Solve this system of equations: y = 7; y = -2x+1 *
2 answers:
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Answer:
The mean of 25 students is 17.6
Step-by-step explanation:
The formula of the mean (average) is mean (average) = , where S is the sum of the data, and N is the number of the data
∵ The average marks of the first 10 students are 17
- That means the mean is 17 and the number of students is 10
∴ Average = 17
∴ N = 10
∵ Average =
- Substitute average by 17 and N by 10
∴ 17 =
- Multiply both sides by 10
∴ 170 = S
∴ The sum of the marks of the first 10 students is 170
∵ The average of the next 15 students is 18
∴ Average = 18
∴ N = 15
- Substitute average by 18 and N by 15
∴ 18 =
- Multiply both sides by 15
∴ 270 = S
∴ The sum of the marks of the next 15 students is 270
Now to find the mean of 25 students and the two sums and divide the answer by 25
∵ S = 170 + 270
∴ S = 440
∵ N = 25
∴ Mean =
∴ Mean = 17.6
The mean of 25 students is 17.6
The mean of the probability distribution is given by the expected value given by
The variance of the probability distribution is given by
The standard deviation is given by
The variance of the probability distribution is given by
The standard deviation is given by