Problema Solution
At a fair, each ride costs one, two or four tickets. The number of rides that cost two tickets is three times the number of rides that cost one ticket. Also, seven more rides cost four tickets than two tickets. Kimberly who has a book of tickets, goes on a ride at random. If the probability that the ride cost her four tickets is 4/7, how many rides are there at the fair?
Answer provided by our tutors
let no. of rides which cost 1 ticket = x
which cost 2 ticket = y
which cost 4 ticket = z
=> y = 3x
z = y+7
=> z = 3x+7
p(4 ticket) = z/(x+y+z)
=> 4/7 = (3x+7)/(7x+7)
=> 4x+4 = 3x+7
=> x = 3
=> y = 9
=> z = 16
total rides = x+y+z
= 28