maths problem

[daisy32]

can anyone help with this poser THE FIRST 20 CUSTOMERS IN A CAFE SPENT AN AVERAGE OF £2 EACH . AFTER A FURTHER 20 CUSTOMERS ORDER,THE AVERAGE AMOUNT ROSE TO £7 EACH .WHAT WAS THE AVERAGE AMOUNT SPENT BY THE SECOND GROUP OF CUSTOMERS

[quinie]

£4,50?

[quinie]

Ignore that answer. My maths isn't very good

[bibblebub]

after 20 customers, average = £2 => total amount spent = £40

another 20 customers (i.e. 40 in total), average = £7 => total amount spent = £280

thus amount spent by second group of 20 customers = £240 => average = £12

[DTCwordfan]

how can you spend that sort of money in your average caff without having a heart attack

6 pounds

[Buenchico]

The first group spends 20 x £2 = £40
Then, after the new group have joined, the total spend is now 40 x £7 = £280
So the extra money spent by the second group of customers = £280 - £40 = £240
Since 20 people spent £240, their average spend was £240 divided by 20 = £12

Chris

[Buenchico]

I hope that you were one of my pupils when I was teaching maths, Bibblebub ;-)

[DTCwordfan]

sorry 12 pounds

[bibblebub]

chris - for that level of arithmetic you are talking about early to mid 60s

[quinie]

Now I see where I went wrong!