
notice, if the original area was πr², then the new area has a factor in front of it, that much.
Ben drinks 3 1/2 liters of tea every 40 minutes.
This means that he would drink 1 3/4 of tea every 20 minutes (divide both sides by 2).
Now, let's multiply each side by 3.
1.75 * 3 = 5.25 (aka 5 1/4)
20 * 3 = 60 minutes (an hour)
He drinks 5 1/4 liters of tea in one hour.
B would be the correct answer. If you take 4:13 in order to form a ratio equal to that you have to multiply both sides of the ratio by the same number. 4*4=16 and 13*4=52
Answer:
A sample of 1068 is needed.
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 is:

95% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
At 95% confidence, how large a sample should be taken to obtain a margin of error of 0.03 for the estimation of a population proportion?
We need a sample of n.
n is found when M = 0.03.
We have no prior estimate of
, so we use the worst case scenario, which is 
Then






Rounding up
A sample of 1068 is needed.
It is given the probability that a dancer like ballet is 0.35
So, P(B) = 0.35
It is given the probability that a dancer like tap is 0.45
So, P(T)= 0.45
The probability that he likes both ballet and tap is 0.30
So, 
the probability that the dancer likes ballet if we know she likes tap. This is the case of conditional probability.
So, 

= 0.666
= 0.67
Therefore, the probability that the dancer likes ballet if we know she likes tap is 0.67.
Option 3 is the correct answer.