Posted by **rose** on Monday, November 23, 2009 at 5:03pm.

How do you solve this problem? physical therapy reported that it has been estimated that 80 percent of all lower back pain cases are caused by weak trunk muscles. if 15 patients with lower back pain are examined, what's the probability that

1. exactly 10 have pain caused by weak trunk muscles

2. more than 8 have pain caused by weak trunk muscles

3. fewer than 6 have pain caused by weak trunk muscles

- statistics -
**Reiny**, Monday, November 23, 2009 at 5:33pm
1. Prob(pain caused by w.t.m.) = .8

prob(pain not caused by w.t.m.) = .2

so prob(exactly 10 caused by w.t.m.)

= C(15,10)(.8^10)(.2^5)

= .10318

2. lots of calculations here,

more than 8 means

exactly 9 + exactly 10 + exactly 11 + ...+ exactly 15

= C(15,9)(.8^9)(.2^6) + C(15,10)(.8^10)(.2^5) + ... + C(15,15)(.8^15)

2. done in a similar way, except you want

exactly 0 + exactly 1 + .. + exactly 5

= C(15,0)(.2)15 + C(15,1)(.8)(.2^14) + ..

happy calculating.

## Answer This Question

## Related Questions

- Statistics - A survey of physicians in 1979 found that some doctors give a ...
- statistics - Ina study designed to test the effectiveness magnets for treating ...
- Simple Math - Please help me with this problem . It is not hard but I need some ...
- statistics - A residential treatment facility tests a new group therapy for ...
- Math Homework - In a clinical trial, a drug used to relieve pain caused side ...
- grammar - The patient’s first visit, to the office, was for lower back pain.
- Banking Finance - The price of a bond at any given point will be ___________ ...
- Grammar - Select the sentence that does NOT have an agreement error. a. ...
- statistics - In a study designed to test the effectiveness of magnets for ...
- Math - In a clinical trial, a drug used to relieve pain caused side effects in 7...

More Related Questions