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aliina [53]
3 years ago
7

25 scores from all of the students who took the test. She sees that the mean score is 134 with a standard deviation of 6.0547. T

he superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 13. Is there evidence that the standard deviation of test scores has decreas
Mathematics
1 answer:
Tomtit [17]3 years ago
7 0

Answer:

WE fail to reject the Null and conclude that ; Standard deviation of test hasn't decreased.

Step-by-step explanation:

The hypothesis :

H0 : σ = 13

H1 : σ < 13

Using the Chisquare Square statistic :

χ² = (n-1)*s²/σ²

Sample size, n = 25

s² = 6.0547²

σ² = 13²

χ² = (25 - 1)*6.0547² / 13²

χ² = 879.82541016 / 169

χ² = 5.206

The degree of freedom, df = 25 - 1 = 24

The Pvalue(5.206, 24) = 0.99981

Reject H0, if Pvalue < α ;

Since Pvalue > α ; WE fail to reject the Null and conclude that ; Standard deviation of test hasn't decreased.

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Eric was rock climbing. At one point, he stopped and climbed straight down 2\dfrac{1}{2}2
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The equation that matches the given situation is -2\frac{1}{2}+6\frac{3}{4}=? . So, after two moves, Eric's elevation changed 4\frac{1}{4} meters above.

We know that in mathematics, subtraction means removing something from a group or a number of things. What is left in the group gets smaller when we subtract. The minuend is the first element we use. The subtrahend is the part that is being removed. The difference is the portion that remains after subtraction.

Assume that "negative" means climbing down and "positive" means climbing up. We must locate the elevation change in this area.

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Then the change = -2\frac{1}{2}+6\frac{3}{4}

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Therefore, the equation that matches the given situation is -2\frac{1}{2}+6\frac{3}{4}=? . So, after two moves, Eric's elevation changed 4\frac{1}{4} meters above.

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