Math Is Fun Forum

jmoore

Member

Registered: 2008-01-09

Posts: 25

Some Questions that i am not sure how to work out

hey all,

sorry for the lenght of my post i am hoping if somone can help me answer these questions as i am not sure how to work them out.

1) A traffic warden works a 40hr, 5-day week.  How many hours are worked per day?

2) In a drink drive campaign officers were instructed to stop ninety vehicles over a three-day period.  It was then decided to extend this for an extra 7 days.  How many vehicles were stopped in total over the seven extra days? (i came up with 270) but i think it is wrong

3) Ten people were required for a police identity parade.  Of the ten people chosen, one was guilty of the offence, what percentage were innocent?  (my answer was 99% but it said 90% how is that true)

5) What percentage of £60 is £9? (i can never seem to understand percentages, i know my tables kinda so is there anyway i can use my tables to work out percentages)

6) How many 7 x 7cm tiles are needed to cover an area that measures 84 x 84cm?

7) Two out of every eight motorists stopped at a DOT census are questioned.  If 408 motorists are stopped, how many are questioned?

thanks i would be greatfull if you can help

NullRoot

Member

Registered: 2007-11-19

Posts: 162

Re: Some Questions that i am not sure how to work out

Hi J.

A lot of your questions involve division in some way to work out the answer.

1) The warden works 40 hours every week, but her week is only 5 days long (she gets weekends off, probably). So how many hours would you have to work each day for 5 days to get to 40?

40 hours / 5 days = 8 hours.

2) This is very similar to the answer above. 90 cars in 3 days is how many cars a day? Work it out just like I did in #1. Now how many more cars would they check if they checked that many cars each day for 7 days?

3) There are 10 people and 1 is guilty. That means 9 of 10 are innocent, right? So what fraction is innocent then? It's 9/10. It's not random that the line in a fraction looks the same as a division sign. When you see a fraction like 1/2 it literally means "one divided by two". This is important for percentages.
To get a percentage, you need to follow two steps:
First you take a fraction and work out what it is in decimals. So 9/10 is "nine divided by ten", which works out as 0.9.
The next step is to multiply that answer by 100. That turns out to be 90.
There's your percentage! 9/10 innocent people is the same as 90%.

5) Do the steps above, but this time what would your fraction be if you're trying to find 9 out of 60?

6) What's the area of a 7 x 7 tile? Much like fractions, it's not a coincidence that it looks like 7x7 (seven times seven). And the same with 84 x 84! So work out the total area to cover (84x84) and work out the area each single tile covers (7x7). How could you use division to work out how many single tiles fit into that total area?

7) Now you need to learn to use percentages to solve this one. You have two out of every eight. What percent 2 out of 8? The question is saying that the same percentage of 408 is stopped.
But how do you work out that percentage of 408? You divide the percentage by 100 and then multiply that answer to the 408.

Here's a similar example:
25% of 200 people are stopped and asked a question. How many people were asked a question?
First, divide the percentage by 100...
25 / 100 = 0.25

Now multiply that answer by the 200 people...
0.25 x 200 = 50

So 50 people were stopped and asked a question!

Hope that helps you not only solve the problems but understand the methods a bit better.

Last edited by NullRoot (2008-01-14 23:30:57)

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Trillian: Five to one against and falling. Four to one against and falling… Three to one, two, one. Probability factor of one to one. We have normality. I repeat, we have normality. Anything you still can’t cope with is therefore your own problem.

jmoore

Member

Registered: 2008-01-09

Posts: 25

Re: Some Questions that i am not sure how to work out

Hey Null,

I seem to have trouble dividing like the final question i got it down to 0.4 and then times by 8 gives me 32% is that correct lol or am i miles out maths is not my strongest subject as you can tell

NullRoot

Member

Registered: 2007-11-19

Posts: 162

Re: Some Questions that i am not sure how to work out

No problem, J.

I'll walk through the last one with you.

First we need to identify what percentage is 2 out of 8. First, divide 2 by 8...
2 ÷ 8 = 0.25

Now that we have 0.25, multiply it by 100 to obtain the percentage.
0.25 x 100 = 25

So 2 is 25% of 8. That's the percentage of people they check, 25%.

It then says that 408 people pass by the census. To find out what 25% of 408 is, you need to divide the 25% by 100 and then multiply that answer to 408.

25 ÷ 100 = 0.25

0.25 x 408 = 102

So 102 people would have been stopped.

Last edited by NullRoot (2008-01-15 01:01:53)

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Trillian: Five to one against and falling. Four to one against and falling… Three to one, two, one. Probability factor of one to one. We have normality. I repeat, we have normality. Anything you still can’t cope with is therefore your own problem.

jmoore

Member

Registered: 2008-01-09

Posts: 25

Re: Some Questions that i am not sure how to work out

ok i can understand slightly now however i have problems when it comes to the division as for this practive test i am not allowed to use a caluculator heres another one 5/10 * 100 what i would do is 5/10 = 2 becuase 5*2=10 now that i have 2 i would times it by 100 which would = 200% but to me it don't look right,

so if you know of any sites that would help me with my division that would provide tutorials with step by step guides then please let me know

p.s.

i have looked at the division tutorials on this site but they are over my head and not detailed enought lol

i really appricate you helping me kind sir

j

Last edited by jmoore (2008-01-15 01:21:54)

NullRoot

Member

Registered: 2007-11-19

Posts: 162

Re: Some Questions that i am not sure how to work out

Ah. You are doing it slightly backwards.

When you have X / Y, then you are trying to find something that you can multiply to the bottom number to get the top number.

10 / 5 = 2 because 5*2 = 10

5 / 10 = 0.2 because 10*0.2 = 5

If you can't use a calculator, you should try and find a website where you can polish up on long division and multiplying with decimals. If you find difficulty with those, speak with your teacher. I'm sure he/she'll be happy to help.

After all, failing students ultimately looks bad on one person: the teacher.

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Trillian: Five to one against and falling. Four to one against and falling… Three to one, two, one. Probability factor of one to one. We have normality. I repeat, we have normality. Anything you still can’t cope with is therefore your own problem.