A warehouse contains ten printing machines, four of which are defective. A company selects five of the machines at random, thinking all are in working condition. The company repairs the defective ones at a cost of $20 each. In what interval would you expect the repair costs on these five machines in dollars to lie 75% of the time

Step-by-step explanation:

There from ypergemetric distribution

mean number of defective in sample =n×m/N =5×4/10=2

and std deviation =sqrt(mn/N*(1-m/N)*(N-n)/(N-1))

=sqrt(5*4/10*(1-4/10)*(10-5)/(10-1))=0.816

from Tchebysheff's theorem ; 75% values fall within 2 standard deviation from mean

therefore interval in terms of defective

=2-2*0.816 ; 2+2*0.816 =0.367 ; 3.633

interval in terms of  repair costs =20*0.367 ; 20*3.633 =$7.34 ; $ 72.66

step-by-step explanation: