Answer: The standard deviation was calculated incorrectly.
Step-by-step explanation:
- The standard deviation measures the dispersion of the data values from the mean value.
It cannot be negative , because it is the square root of the variance .
We add all squared deviations from the data points away from the mean and (then divide it by the number of data values) to evaluate variance.
Since , any squared number cannot give a negative result.
⇒ Standard deviation cannot be negative.
⇒The standard deviation was calculated incorrectly.
Rest other things (given in options) can not be interpreted on the basis of given information.
21r < 7
Divide by 21
r < 7/21
it will be twelve and thirty eight hundredths
Answer: The test contains 10 three-point questions and 14 five-point questions.
Step-by-step explanation:
Let x represent the number of 3-point questions.
Let y represent the number of 5-point questions.
The maths test consists of 24 questions. This means that
x + y = 24
Each question is worth either 3 points or 5 and the test is worth 100 points. This means that
3x + 5y = 100 - - - - - - - - - - -1
Substituting x = 24 - y into equation 1, it becomes
3(24 - y) + 5y = 100
72 - 3y + 5y = 100
- 3y + 5y = 100 - 72
2y = 28
y = 28/2 = 14
Substituting y = 14 into x = 24 - y , it becomes
x = 24 - 14 = 10
