Solving probabilities that involves percentage.

I'm weak when it comes to solving probability questions that has to do with percentage. please help me.

1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:

(a) 5 will have a muscular dystrophy

(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:

(a) 1 is defective

(b) None of the bolts is defective

At most 2 bolts will be defective

tq

Re: Solving probabilities that involves percentage.

Quote:

Originally Posted by

**fara** I'm weak when it comes to solving probability questions that has to do with percentage. please help me.

1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:

(a) 5 will have a muscular dystrophy

(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:

(a) 1 is defective

(b) None of the bolts is defective

At most 2 bolts will be defective

tq

a) Each child has a 1/4 chance of getting the disease, so the probability of all of them having the disease is 1/4 x 1/4 x 1/4 x 1/4 x 1/4 = (1/4)^5.

Re: Solving probabilities that involves percentage.

Quote:

Originally Posted by

**fara** 1. Muscular dystrophy is a genetically controlled disease. The probability of having this disease in any new born of a specific parents is 25%. If the couple has 5 children, find the probabilities that:

(a) 5 will have a muscular dystrophy

(b) Fewer than 2 will have a muscular dystrophy

2. If 20% of the bolts produced by a machine are defective, determine the probability that out of 4 bolts:

(a) 1 is defective

(b) None of the bolts is defective

At most 2 bolts will be defective

tq

HINTS:

1b) 0.63281

2a) 0.4096

2b) 0.4096

2c) 0.9728

Re: Solving probabilities that involves percentage.

Quote:

Originally Posted by

**MaxJasper** HINTS:

1b) 0.63281

2a) 0.4096

2b) 0.4096

2c) 0.9728

Those aren't hints, those are answers. Answers which the OP most likely already has if he/she looks in the back of the book for.

A hint is something which gives the OP some direction to solve the problem him/herself. Such as for 1.b) you will need to use the Binomial Distribution.