Answer: 231
<u>Explanation:</u>
Liwen Celina
5x 6x
5x - 21 =
6x
5x - 21 = 4x
<u>-4x +21</u> <u>-4x +21 </u>
x = 21
Liwen: 5x = 5(21) = 105
Celina: 6x = 6(21) =<u> 126</u>
Total: 231
Answer: About 191 students scored between a 60 and an 80.
Step-by-step explanation:
Given : A set of 200 test scores are normally distributed with a mean of 70 and a standard deviation of 5.
i.e.
and 
let x be the random variable that denotes the test scores.
Then, the probability that the students scored between a 60 and an 80 :

The number of students scored between a 60 and an 80 = 0.9544 x 200
= 190.88 ≈ 191
Hence , about 191 students scored between a 60 and an 80.
Answer:
The alternative hypothesis is
.
The critical value is 
Step-by-step explanation:
It is claimed that proportion in favor of proportion A is greater than 60%.
This means that at the null hypothesis, we test if the proportion is of at most 60%, that is:

At the alternative hypothesis, we test if the proportion is more than 60%, that is:

What is (are) the critical value?
The critical value is the value of Z with a p-value 1 subtracted by the standard significance level of 0.05, since we are testing if the mean is more than a value, so, looking at the z-table, 
Vertical or horizontal; it depends on what the function is.
Answer:
1/2
Step-by-step explanation:
Probably of selecting a boy:
20/30 = 2/3
and brought 10 up to 20:
45/60 = 3/4
so Probably of selecting a boy and brought 10 up to 20:
2/3 x 3/4 = 2/4 = 1/2