# Stratified Sampling

• MHB
• alpacalrh

#### alpacalrh

There are three secondary schools in Banley.
The table shows the number of students in each of these schools.
750 700 900

Germaine takes a sample of 50 students stratified by school.
Work out the number of students from Greslow High in the sample.

Re: help

Re: help

Hello,

Really? You post a thread with a completely useless title, and then post a problem with no effort shown, and now you are going to curse and demand we answer...mere minutes after originally posting?

That's not how we do things here...we are here to help you, not do your work for you. (Shake)

So, I will give you a chance to adjust that attitude, and show what you have tried, and then we can see where you are stuck and need guidance. Sound good?

Re: help

alpacalrh, please avoid the use of derogatory language.
But to answer your first post, is it just me that I'm not quite understanding the problem? Could you explain more clearly?

Re: help

Stratified sampling uses proportionate sampling...so this problem boils down to one of ratios. For example, out of the entire population of students from the 3 schools, the portion that are from Adis College is:

$$\displaystyle \frac{750}{750+700+900}=\frac{750}{2350}=\frac{15}{47}$$

So, the number of students in the sample of 50 from Adis College should be a rounding of:

$$\displaystyle \frac{15}{47}\cdot50\approx16$$

And then for Greslow High we would have:

$$\displaystyle \frac{14}{47}\cdot50\approx15$$

And for Fripp School:

$$\displaystyle \frac{18}{47}\cdot50\approx19$$