daffy8
Bunuel
A certain toll station on a highway has 7 tollbooths, and each tollbooth collects $0.75 from each vehicle that passes it. From 6 o'clock yesterday morning to 12 o'clock midnight, vehicles passed each of the tollbooths at the average rate of 4 vehicles per minute. Approximately how much money did the toll station collect during that time period?
A. $1,500
B. $3,000
C. $11,500
D. $23,000
E. $30,000
NEW question from GMAT® Quantitative Review 2019
(PS01443)
why is it 18 hours from 6 to 12, from 6 to 12 means 6 and 12 both are included so it should be 19 hours.
where am I wrong?
There is a similar question in one of the threads " tickets being sold to a group of 30 every 5 minutes FROM 9 am to 5:55 pm and there we have counted 9 and 5:55 both for calculating the 5 minute interval".
Bunuel please explain
Let's look at a simpler example. How many hours are there between 3pm and 5pm?
5 - 3 = 2 hours
On this problem, midnight is the equivalent of 24:00.
So, we subtract: 24 - 6 = 18 hours.
Or, another way to look at it: it's a full 24-hour day, minus the 6 hours before 6am.
On the tickets problem you're referring to, it's counting the number of times we sell tickets, which are spaced out in 5 minute
intervals. This is different, and invokes the +1 concept that you're thinking about, when we're counting the number of values in an evenly spaced set.
Suppose we are asked how much time passed between 9:00am and 9:10am: we simply subtract, and get 10 minutes.
However, if we're asked how many times we sell tickets, if they're sold every 5 minutes from 9:00am to 9:10am, inclusive, then there's still a 10-minute period, with TWO 5-minute breaks between sales, but we have sold tickets THREE times: 9:00, 9:05, and 9:10. The difference here is that we need to count the sales at each endpoint. Alternatively, if we are asked for a time interval, we can just subtract the start time from the end time.