# precentage

• May 18th 2008, 02:21 AM
dravid2
precentage
One day, each driver entering a car park paid
exactly £1.50

Machine accepts only £1 coins and 50p coins

Here is what was put into the machine that day.
Number of £1 coins
136

Number of 50p coins
208

On that day, what percentage of drivers paid with three 50p coins?

• May 18th 2008, 02:35 AM
angel.white
Quote:

Originally Posted by dravid2
One day, each driver entering a car park paid
exactly £1.50

Machine accepts only £1 coins and 50p coins

Here is what was put into the machine that day.
Number of £1 coins
136

Number of 50p coins
208

On that day, what percentage of drivers paid with three 50p coins?

Because every driver who paid £1.5 with a £1 coin must have also paid with a single 50p coin, you know that that 136 of the 50p coins must have been paid by the drivers who did not pay three 50p coins. So 208-136 = 72.

So 72 of the 50p coins must have been paid by drivers who paid three 50p coins.

Since each driver who paid with 50p coins paid three, then you know that there are one third as many drivers as coins, so 72/3 = 24

So we have the total number of drivers being 136+24 = 160

and the percentage of drivers who paid with 50p coins is 24 divided by 160 = .15

So 15% of the drivers paid with three 50p coins.
• May 18th 2008, 03:44 AM
dravid2
OH i get it now, tar dude u r an absolute legend!