GCSE Maths Help and Chat Thread

Original post by NothingButWaleed

What does tagging do?

It just means that you received a notification that directed you to this thread.

Reply 21

Original post by notnek

It just means that you received a notification that directed you to this thread.

oh ok

Reply 22

Original post by NothingButWaleed

If half the machines are used it would take double the time to make all the bottles, hence, 4 machines would take 10 days!

That's right. But you are told that the 4 machines worked for 2 days so they can't have made all the bottles. How much of the bottles did they make?

Original post by NothingButWaleed

If half the machines are used it would take double the time to make all the bottles, hence, 4 machines would take 10 days!

That would be the case if only 4 machines were in operation for the entirety of the time that it takes for the bottles to be manufactured.

However,

From the 3rd day, all 8 machines are used to make the bottles.

How can you use your deduction that 8 machines take half as long as 4 machines to create the same amount of bottles?

Reply 24

Original post by notnek

That's right. But you are told that the 4 machines worked for 2 days so they can't have made all the bottles. How much of the bottles did they make?

i dont know

Reply 25

Original post by _gcx

That would be the case if only 4 machines were in operation for the entirety of the time that it takes for the bottles to be manufactured.

However,

How can you use your deduction that 8 machines take half as long as 4 machines to create the same amount of bottles?

What does "deduction" mean?

Reply 26

Original post by NothingButWaleed

i dont know

Ignore what I said. @_gcx will help you solve the question in a better way.

Reply 27

Original post by notnek

Ignore what I said. @_gcx will help you solve the question in a better way.

But i dont understand what he is talking about!

Reply 28

Original post by _gcx

That would be the case if only 4 machines were in operation for the entirety of the time that it takes for the bottles to be manufactured.

However,

How can you use your deduction that 8 machines take half as long as 4 machines to create the same amount of bottles?

Maybe multiply it by 2?

Original post by NothingButWaleed

i dont know

We know that 1 day with 8 machines will produce the same amount of bottles as 2 days with 4 machines. How can we use this information to work out how long it takes running with 4 machines for 2 days, then 8 machines after that?

Reply 30

Original post by NothingButWaleed

But i dont understand what he is talking about!

This is a tough question that most found hard - you just need a bit more explanantion and I think you'll get it, you just need to be patient! I can help later if _gcx isn't free.

Reply 31

Original post by _gcx

We know that 1 day with 8 machines will produce the same amount of bottles as 2 days with 4 machines. How can we use this information to work out how long it takes running with 4 machines for 2 days, then 8 machines after that?

I would use ratios...

1 day :8 machines = same amount of bottles
2 days:4 machines = same amount of bottles

So..
4 days:2 machines = same amount of bottles
?????

Original post by NothingButWaleed

I would use ratios...

1 day :8 machines = same amount of bottles
2 days:4 machines = same amount of bottles

So..
4 days:2 machines = same amount of bottles
?????

This might be a better way to think about it: Think of the 5 days as a countdown.

Every day at half efficiency (4 machines) subtracts half (for essentially a half day's work).

Every day at full efficiency (8 machines) subtracts one (for a full day's work)

Reply 33

Original post by _gcx

this might be a better way to think about it: Think of the 5 days as a countdown.

Every day at half efficiency (4 machines) subtracts half (for essentially a half day's work).

Every day at full efficiency (8 machines) subtracts one (for a full day's work)

whaaatttt???

Reply 34

Original post by NothingButWaleed

I would use ratios...

1 day :8 machines = same amount of bottles
2 days:4 machines = same amount of bottles

So..
4 days:2 machines = same amount of bottles
?????

Do you agree that 4 machines in 2 days make the same amount of bottles as 8 machines in 1 day?

So if you like we can replace "4 machines in 2 days" to "8 machines in 1 day" in the question. So the question becomes:

The 8 machines in the factory could make all the bottles in 5 days.
All the machines work at the same rate.

Stage 1 : For 1 day, 8 machines are used to make the bottles.
Stage 2: All 8 machines are used to make the bottles.

How long wil stage 2 take?

Reply 35

Original post by notnek

Do you agree that 4 machines in 2 days make the same amount of bottles as 8 machines in 1 day?

So if you like we can replace "4 machines in 2 days" to "8 machines in 1 day" in the question. So the question becomes:

The 8 machines in the factory could make all the bottles in 5 days.
All the machines work at the same rate.

Stage 1 : For 1 day, 8 machines are used to make the bottles.
Stage 2: All 8 machines are used to make the bottles.

How long wil stage 2 take?

5 days

Reply 36

Original post by notnek

Do you agree that 4 machines in 2 days make the same amount of bottles as 8 machines in 1 day?

So if you like we can replace "4 machines in 2 days" to "8 machines in 1 day" in the question. So the question becomes:

The 8 machines in the factory could make all the bottles in 5 days.
All the machines work at the same rate.

Stage 1 : For 1 day, 8 machines are used to make the bottles.
Stage 2: All 8 machines are used to make the bottles.

How long wil stage 2 take?

OHHHHHHHHHHH.....
so 1 day for 8 bottles and 5 days for the rest so 1+5 = 6 days in total!
This is such a good way to understand it the other ways were so confusing

Reply 37

Original post by NothingButWaleed

5 days

No, notice that stage 1 took 1 day and 8 machines make all the bottles in 5 days. So how many extra days are needed for stage 2?

Reply 38