Posted by HM on .
A batch consists of 12 defective coils and 88 good ones. find the probability of getting two good coils when two coils are randomly selected if the first selection is replaced before the second is made.
Help me..
since it would be replaced would the answer be 0.7744 ?

PROBABILITY MATH 
drwls,
No. (76/88)^2 = 0.7459

PROBABILITY MATH 
HM,
how is it going to be 76/88 ?

PROBABILITY MATH 
drwls,
It isn't. For two draws, it is the square of that.
There are 76 good coils out of 88. What does that tell you about the probabiloity of selecting a good one at random each time? 
PROBABILITY MATH 
HM,
My answer was correct.. Your answer is not in the choices :S

PROBABILITY MATH 
Reiny,
There are a total of 100 coils, of which 88 are good
prob of getting 2 good ones in a row, after replacing the first
= (88/100)(88/100)
= (88/100)^2
= .7744 
PROBABILITY MATH 
HM,
Thank you Reiny, that is what I thought.
Drwls I appreciate your effort anyway :) 
PROBABILITY MATH 
nagwa,
a batch consists of 12 defective clocks and 88 good ones find the probability of getting two good clocks when the two are randomly selected if the first selection is replaced before the second selection is made.
B the first selection is not replaced.