Answer:
0.3595, 0.9571,0.1078,0.00899
Step-by-step explanation:
Given that a junk box in your room contains eighteen old batteries, seven of which are totally dead.
To find out the following probabilities
a) Prob the first two are good =Prob of selecting 2 from 11 good batteries
= [tex]\frac{11C2}{18C2} =\frac{110}{18(17)} \\=0.3595[/tex]
b) Atleast one of the first three works
=P(1 or 2 or 3) = 1-P(0)
= [tex]1-\frac{7C3}{18C3} \\=0.9571[/tex]
c) The first four work = Prob of picking all 4 from 11 good ones
=[tex]\frac{11C4}{18C4} \\=0.1078[/tex]
d) You have to pick five batteries to find one that works.
= Prob first 4 are defective and 5th is good
= [tex]\frac{7C4}{18C4} *\frac{11C1}{14C1}[/tex] =0.00899
(This is because once 4 defective removed we have remaining 3 defective and 11 good in total 14)
