Answer:
b=9,a=12
Step-by-step explanation:
I solved by substitution:
b = 3/4a ---> plug this into the other equation
a + b = 21 is now a + 3/4a = 21
Reduce: 7/4a = 21
a = 12
Now solve for b:
b=3/4a is now b=3/4(12)
b=9
Answer: m
explanation: jsjwjwjsiw
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, 