Answer:
Swimming speed in still water is approximately 1.5 mph
Step-by-step explanation:
Given the speed of the current = 1 mph
distance she swims upstream =2 miles,
the total time = 5 hours.
She swam 2 miles upstream against the current and 2 miles back to the dock with the current. The formula that relates distance, time, and rate is 
Let x be the speed in still water.
Then her speed with the current is x + 1, and
her speed against the current is x – 1.
Total time is equal to 2 miles with upstream and 2 miles downstream.

Now Using quadratic formula to solve above equation we get;

Since speed must be positive, Hence speed of still water is about 1.5 miles per hour.
The answer is a chemical reaction
Answer:
80
Step-by-step explanation:
So if 50 tablets are made and 2 are defective then it’s 50:2. That means for every 50 tablets are made 2 are defective. And since 50 goes into 2000 40 times, you would multiply 40 x 2 to get 80, the number defective tablets
Answer:
n=1849
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The population proportion have the following distribution
Solution to the problem
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by
and
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that
and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
Assuming that the proportion is estimated
. And replacing into equation (b) the values from part a we got:
And rounded up we have that n=1849