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Giving a test to a group of students, the grades and gender are summarized below

A B C Total

Male 19 4 12 35

Female 3 13 5 21

Total 22 17 17 56

Let pp represent the percentage of all male students who would receive a grade of A on this test. Use a 99.5% confidence interval to estimate p to three decimal places.

Enter your answer as a tri-linear inequality using decimals (not percents).

< p

Respuesta :

akiran007

Answer:

Using Anova for a tri linear probability at ∝= 0.005

Step-by-step explanation:

Here simple probability cannot be used because  we want to enter your answer as a tri-linear inequality using decimals (not percents).

So we can use ANOVA

Null hypothesis

H0: µA = µB=µC

all the means are equal

Alternative hypothesis

H1: Not all means are equal.

The significance level is set at α-0.005

The test statistic to use is

F = sb²/ sw²

Which if H0 is true has an F distribution with v₁=k-1 and v₂= n-k degrees of freedom .

The computations are as follows

                     XA (XA)²            XB (XB)²         XC (XC)²       Total   ∑X²

Male                   19(361)          4(16)                 12(144)           35     521    

Female               3(9)                13 (169)           5  (25)            21      203  

TotalTj                  22                   17                      17              56     724

T²j                       (22)(22)

                             484                 289                  289        1062  

∑X²                     370               285                     169

Correction Factor = CF = Tj²/n = (56)²/6= 522.67

Total SS ∑∑X²- C. F = 724- 522.67= 201.33

Between SS ∑T²j/r - C.F = 1062/ 2 - 522.877 =8.33

Within SS = Total SS - Between SS

=201.33- 8.33= 193

The Analysis of Variance Table is

Source Of                Sum of          Mean         Computed

Variation        d.f    Squares      Squares                    F

Between

Samples           1        8.33               8.33           8.33/ 48.25= 0.1726

Within

Samples          4       193              48.25                                  

The critical region is F >F ₀.₀₀₅ (1,4) = 31.3328

Calculated value of F = 0.1726

Since it is smaller than 5 %  reject H0.

However the decimal probability will be

Male 19 4 12 35

Female 3 13 5 21

Total 22 17 17 56

There are total 22 people who get an A but only 19 males who get an A

So the probability that a male gets an A is = 19/22= 0.8636