Simplify 6(x + 3). 6x + 3 x + 18 6x + 18 6x + 9
1 answer:
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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
Answer:
The rate of the jet in still air = 1030 miles per hour
And 210 miles per hour is the rate of the stream.
Step-by-step explanation:
Let the speed of the jet in still air be miles per hour.
And,the speed of the jetstream be miles per hour.
Key:So when it is moving against the stream speed will be and when it is moving with the stream, speed will be
And we know that.
Distance=Speed multiplied with time.
Arranging the equation.
...equation 1
...equation 2
Working with the equation by using elimination method.
Dividing equation 1 with 8 and equation 2 with 9.We will have
1240=...eqn 3
820=...eqn 4
Now adding both the equation will decimate y.
1240+820=2
2060=2
Dividing with 2 both sides.
1030=
By plugging the value of we can find y in equation 3.
1240=1030 +
Subtracting 1030 from both sides.
1240-1030=
=210 miles per hour
So the rate of the jet in still air = 1030 miles per hour
And 210 miles per hour is the rate of the jet stream.