Answer:
No of white balls = 5
Step-by-step explanation:
Given that,
Total no of red balls = 4
Total no of green balls = 6
The probability of not drawing a white ball in one draw be, 
We need to find the number of white balls. Let there are x balls.
The probability of drawing a white ball = 1 - the probability of not drawing a white ball
= 1 -2/3
= 1/3
Using the formula for solving probability of having a white ball.

Hence, there are 5 white balls.
1 hour = 60 minutes.
60 minutes / 20 minutes = 3.
55 people x 3 = 165 people per hour. (Rate per hour)
165 people x 3 hours = 495 people. (Total people in 3 hours)
To get the answer, all you have to do is divide 11.70 by 9 to get
$1.30
Hope this helps :)