Nearly 7,000 children acquired disease Z in the last year. Among the population of all children who acquired disease Z in the last year, suppose that (unknown to researchers) 1400 of them (20%) also acquired a secondary skin infection. A researcher intends to take a simple random sample of 50 children who had the disease last year and record whether or not the person also had a secondary infection. Let X be the number of children in the sample who report having a secondary infection. The variance of this distribution is .

disease z is pretty deadly

Step-by-step explanation:

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have