stats

Head lice can be a problem in classrooms. From the past experience, suppose it is predicted that 5% of the students will get lice if there are some reported cases. The health nurse checks 120 randomly chosen students and records the number of students that have head lice. What is the probability that exactly 6, 7, 8 students in the random sample have head ice?”

How would I do this question??

I presume you mean that there is a 5% chance that a student, drawn at random, will have lice.

You could solve this exactly as a combinatorial problem. The probability of seeing exactly 6 is:
(.95^114 * .05^6)*Z, where Z is 120!/(6!*114!) (where ! means factorial). Repeat for exactly 7 and exactly 8.

Or you could solve approximately and use the properties of a binominal distribution. Here, the expected mean is .05*120=6, the standard deviation is sqrt(120*.05*95)=2.37 So, 8 is .84 standard deviations away from the mean. Use a cumulative normal distribution table to find your probability. (But, I wouldnt use 8, I would use 8.5)

1. 👍 0
2. 👎 0
3. 👁 65

Similar Questions

1. Math

The table shows the number of classrooms needed for different numbers of students. Total Students Classrooms 66 3 110 5 154 7 220 10 What is the relationship between Total Students and Classrooms? A.Classrooms=Total Students

asked by Colton on February 21, 2012
2. Grammar

Mother wondered from __________ her children had gotten the head lice. A) who B) whom I answered b

asked by Marie on November 14, 2012
3. philosophy

Please formalize the argument given in the following passage. For all inferences from experience suppose, as their foundation, that the future will resemble the past, and that similar powers will be conjoined with similar sensible

asked by cv on June 27, 2015
4. English

I have to write my cure for an "ill" that plague teenagers. This one poem provides a good example of what I'm trying to do. I t is calles Scrawny's surfire ance cure. The plague in it was zits, and the cure it suggested was First

asked by Sara on May 3, 2010
5. childcare

14. Caregivers shouldn't allow dress-up play with hats when _______ is/are a problem. A. cradle cap B. dandruff C. lice D. psoriasis

asked by Heather on April 7, 2011
6. Math

School A has 480 students and 16 classrooms. School b has 192 students and 12 classrooms. A. what is the ratio of students to classrooms at School A? 480:16 B. what is the ratio of students to classrooms at School B? 192:12 C. How

asked by Jay on April 17, 2015
7. general question

What are 3 pros and 3 cons for technology in children's classrooms? I really cant think of any other than that there aren't much computers in the classrooms(maybe like 1 or 2)

asked by Trish on March 9, 2016
8. Science-Physics: Space Station

Hello, I am having trouble with this physics problem. Any suggestions with this? Sketch and calculate a spacestation that would meet the requirement of having a 2m tall person experience a 10 % difference in centripetal

asked by Gerald on October 11, 2006
9. Writing

I have given a expository essay to wire about time travel to visit past or future. I decided to go past to experience Revolutionary War. Now I am stuck with 2 strong reasons. Could someone help me on this please. Thank you for

asked by Cole on March 21, 2017
10. Math

School A has 480 students and 16 classrooms, School B has 192 students and 12 classrooms. How many students would have to transfer from School A to School B for the ratios of students to classrooms at both schools to be the same?

asked by Jay on April 18, 2015

More Similar Questions