44
Step-by-step explanation:
let boys be x and girls be y
x/y=5/6
x=5y/6....(1)
if 6 boys join the club that will be x+6
Therefore:
(x+6)/y=13/12
13y=12x+72
13y-12x=72
Recall x=5y/6
Therefore:
13y-12(5y/6)=72
13y-(2*5y)=72
13y-10y=72
3y=72
y=24 people
Therefore:
x=(5*24)/6
x=20 people
Therefore people in the club before are 20+24=44
This is the answer ......
Answer:
C. H0 : p = 0.8 H 1 : p ≠ 0.8
The test is:_____.
c. two-tailed
The test statistic is:______p ± z (base alpha by 2) 
The p-value is:_____. 0.09887
Based on this we:_____.
B. Reject the null hypothesis.
Step-by-step explanation:
We formulate null and alternative hypotheses as proportion of people who own cats is significantly different than 80%.
H0 : p = 0.8 H 1 : p ≠ 0.8
The alternative hypothesis H1 is that the 80% of the proportion is different and null hypothesis is , it is same.
For a two tailed test for significance level = 0.2 we have critical value ± 1.28.
We have alpha equal to 0.2 for a two tailed test . We divided alpha with 2 to get the answer for a two tailed test. When divided by two it gives 0.1 and the corresponding value is ± 1.28
The test statistic is
p ± z (base alpha by 2) 
Where p = 0.8 , q = 1-p= 1-0.8= 0.2
n= 200
Putting the values
0.8 ± 1.28 
0.8 ± 0.03620
0.8362, 0.7638
As the calculated value of z lies within the critical region we reject the null hypothesis.