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# Ratios watch

1. Can someone PLEASE help me! I am currently doing a maths GCSE via open learning and i'm stuck on ratios. can someone help break this example question down for me really really simply?

A man who smokes 15 cigarettes a day, finds that 24 packets will last him 32 days. If he cuts down to only 12 a day, and buys 18 packets, how long will they last?

Number of cigarettes smoked per daydecreased in ratio 12:15 = 4:5
(I understand this)

Number of days they will last will increase in ratio 5:4
(How do they come to this conclusion)

Number of packets bought decreases in ratio 18:24 = 3:4
(I understand how you get these figures too)

Time they will last also decreases in ratio 3:4
(I have no idea why this is?)

Hence the time they will last = 30 days

How can I work this equation out. This explanation is confusing me!

Thanks

Garrie
2. (Original post by garrierobert)
Can someone PLEASE help me! I am currently doing a maths GCSE via open learning and i'm stuck on ratios. can someone help break this example question down for me really really simply?

A man who smokes 15 cigarettes a day, finds that 24 packets will last him 32 days. If he cuts down to only 12 a day, and buys 18 packets, how long will they last?

Number of cigarettes smoked per daydecreased in ratio 12:15 = 4:5
(I understand this)

Number of days they will last will increase in ratio 5:4
(How do they come to this conclusion)

Number of packets bought decreases in ratio 18:24 = 3:4
(I understand how you get these figures too)

Time they will last also decreases in ratio 3:4
(I have no idea why this is?)

Hence the time they will last = 30 days

How can I work this equation out. This explanation is confusing me!

Thanks

Garrie
Are you sure ratios are required here?

I think the implication in the question is that if he smokes 15 a day for 32 days, he must smoke 15 x 32 = 480. If 480 cigarettes is 24 packets, that's 20 per pack. If he only buys 18 packets, in total that's 360 cigarettes. Smoking 12 a day, means that it would take him 30 days to smoke them all.

The question does not contain ratios, so maybe you don't have to use them!

Is that clear?
3. Of course he'd be better off not smoking at all, since there aren't any benefits...

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