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Twenty middle school students are outside a movie theater waiting for it to open. There are four more girls than

boys in the crowd. If they are randomly distributed, what is the probability that when the doors open the first

student to get to the ticket counter will be a boy?



If there are two girls who are both named Tina, what is the probability that the last person in line is named Tina?

Respuesta :

Answer:

0.4 , 0.1

Step-by-step explanation:

Let number of boys be = b , number of girls = b + 4 . As total students = 20    b + b + 4 = 20  → 2b + 4 = 20 → 2b = 20 - 4 = 16 → b = 16 / 2 = 8 (boys) , so girls = 12

Prob (a random first child is a boy) = boys / total students = 8 c 1 / 20 c1, or =  8  / 20  = 0.4

Prob ( a 'Tina' out of two Tina is the last) = 2 c 1 / 20 c 1 , or = 2 / 20 = 0.1

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