so 5 people work each one for 21 minutes, that means 21+21+21+21+21 minutes altogether, namely 105 minutes, it took that long for 7 walls, hmmmm how long for just one wall then? well, 105 ÷ 7, namely 15 minutes then, for just 1 wall.
now, if it takes 15 minutes of work to do one wall, what about 5 walls? well, that'd be 15*5 or 75 minutes.
so if we have 3 folks working, how much would each one work? well, 75 ÷ 3, namely 25 minutes, so each of them will work 25 minutes, namely 25+25+25 minutes, so in 25 minutes, they'll be done with 5 walls.
Answer:
The observed tumor counts for the two populations of mice are:
Type A mice = 10 * 12 = 120 counts
Type B mice = 13 * 12 = 156 counts
Step-by-step explanation:
Since type B mice are related to type A mice and given that type A mice have tumor counts that are approximately Poisson-distributed with a mean of 12, we can then assume that the mean of type A mice tumor count rate is equal to the mean of type B mice tumor count rate.
This is because the Poisson distribution can be used to approximate the the mean and variance of unknown data (type B mice count rate) using known data (type A mice tumor count rate). And the Poisson distribution gives the probability of an occurrence within a specified time interval.
Answer:
33.33% probability that it takes Isabella more than 11 minutes to wait for the bus
Step-by-step explanation:
An uniform probability is a case of probability in which each outcome is equally as likely.
For this situation, we have a lower limit of the distribution that we call a and an upper limit that we call b.
The probability that we find a value X lower than x is given by the following formula.

For this problem, we have that:
Uniformly distributed between 3 minutes and 15 minutes:
So 
What is the probability that it takes Isabella more than 11 minutes to wait for the bus?
Either she has to wait 11 or less minutes for the bus, or she has to wait more than 11 minutes. The sum of these probabilities is 1. So

We want P(X > 11). So

33.33% probability that it takes Isabella more than 11 minutes to wait for the bus
Answer:
The 95% confidence interval for the percentage of all boards in this shipment that fall outside the specification is (1.8%, 6.2%).
Step-by-step explanation:
In a random sample of 300 boards the number of boards that fall outside the specification is 12.
Compute the sample proportion of boards that fall outside the specification in this sample as follows:

The (1 - <em>α</em>)% confidence interval for population proportion <em>p</em> is:

The critical value of <em>z</em> for 95% confidence level is,

*Use a <em>z</em>-table.
Compute the 95% confidence interval for the proportion of all boards in this shipment that fall outside the specification as follows:

Thus, the 95% confidence interval for the proportion of all boards in this shipment that fall outside the specification is (1.8%, 6.2%).