Answer:
1
Step-by-step explanation:
1
Answer: 31 3/7
Step-by-step explanation: Simply just multiply 66 by 10 = 660 and then divide 660 by 21 and you get 31 3/7!
X will be the speed of species b and 4x will be the speed of species a:
x + 4x = 180
5x = 180
x = 180 / 5
x = 36 m/h
If species b has a speed of 36 m/h, the speed of species a is 4 times that:
4 x 36 = 144 m/h.
Answer:

Hope it helped,
Happy homework/ study/ exam!
Answer:
We need a sample of at least 752 students.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
The margin of error of the interval is:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
How large of a sample must she have to get a margin of error less than 0.03
We need a sample of at least n students.
n is found when M = 0.03.
We have no information about the true proportion, so we use
.






Rounding up
We need a sample of at least 752 students.