C

1003041603

Level: 
C
There are 30 students in a class, of them are 14 girls and the rest are boys. The teacher selects two students for weekly routine help. If selection is done at random, what is the probability that these students are not two girls? Round the result to two decimal places.
(162)+(161)(141)(302)0.79
(162)(302)0.28
(142)(302)0.21
(161)(141)(302)0.51

1003041602

Level: 
C
A box contains 50 transistors and 4 of them are lower quality. From all transistors 5 are selected at random for inspection. What is the probability that of lower quality is at most one of the selected transistors? Round the result to two decimal places.
(465)+(464)(41)(505)0.96
46!41!+46!42!50!45!0.66
(465)+(464)(505)0.72
46!41!+46!42!4!3!50!45!0.71