Answer:
38.46%
Step-by-step explanation:
There are no names or marking that can make the calculator look different, so the order is not important. Then we should use a combination to solve this problem.
There are 40 calculators in one shipment, 37 of them good items and 3 of them are defect items. We need to choose 19 good calculators and 1 defect calculator. The number of ways to do that will be:
[tex]\frac{37}{19}[/tex]* [tex]\frac{3}{1}[/tex]= 37![tex]\frac{37!}{19!(37-19!)} * \frac{3!}{1!(3-1)!}[/tex]= 53017895700
The number of possible ways to choose 20 calculators out of 40 calculators will be:
[tex]\frac{40}{20}[/tex]= [tex]\frac{40!}{20!(40-20!)}[/tex]=137846528820
The chance will be: 53017895700/ 137846528820 = 0.3846= 38.46%
