Posted by **miriam** on Thursday, March 31, 2011 at 12:40am.

of all 3-to 5-year- old children, 56% are enrolled in school. If a sample of 500 such children is randomly selected, find the probability that at least 250 will be enrolled in school.

- statistics -
**MathGuru**, Thursday, March 31, 2011 at 11:21am
Find mean and standard deviation. Use z-scores to find z, then a z-table to find your probability based on the z-score. This is a normal approximation to the binomial distribution.

I'll get you started:

mean = np = (500)(.56) = ?

standard deviation = √npq = √(500)(.56)(.44) = ?

Note: q = 1 - p

Finish the calculations.

To find z-score:

z = (x - mean)/sd

Note: x = 250

Once you have the z-score, look in a z-table using the score to find your probability. Remember that the question is asking "at least 250" when looking at the table.

- statistics -
**Anonymous**, Wednesday, April 11, 2012 at 4:33pm
.243

## Answer this Question

## Related Questions

- statistics - Of all 3- to 5-year old children, 56% are enrolled in school (p=0....
- finite math - According to a certain countries 44.5% of 3 year olds are enrolled...
- finite math - According to a certain countries 43.8% of 3 year olds are enrolled...
- finite math - According to a certain countries 44.5% of 3 year olds are ...
- Mathematics - Among 500 freshmen pursuing a business degree at a university, 313...
- English - I left out three sentences on the use of "enrol" 1) I signed up for/I ...
- Math - A certain school’s enrollment increased 5% this year over last year’s ...
- math - In a local school 34 students are enrolled in a math class, 85 are ...
- Math - A certain school’s enrollment increased 5% this year over last year’s ...
- Statistics - In an elementary school, 25% of children wear glasses. Suppose that...