# Histograms

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#1
Hi can someone please explain this to me I’m really stuck thank you
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#2
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9 months ago
#3
What are you stuck with/how far have you got?
Do you know the formula for histograms?
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#4
I got 119.5 somehow but the answer was 160 but the mark scheme does not explain the method so I’m confused on the method. I know the topic histograms fairly ok, I was just stuck on this question
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9 months ago
#5
(Original post by gcsesarehard9)
I got 119.5 somehow but the answer was 160 but the mark scheme does not explain the method so I’m confused on the method. I know the topic histograms fairly ok, I was just stuck on this question
What did you get for the frequencies 4.5-6 and 6-10?
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9 months ago
#6
(Original post by gcsesarehard9)
I got 119.5 somehow but the answer was 160 but the mark scheme does not explain the method so I’m confused on the method. I know the topic histograms fairly ok, I was just stuck on this question
The key shows you that 25 little squares represent 20 trees, so you should be able to see that the interval 6-10 is at least 6 x 20 = 120 and your answer must be bigger than this so it can't be 119.5.

Can you work out how many more squares you need to count for the complete area, and therefore how many trees are included?
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#7
(Original post by davros)
The key shows you that 25 little squares represent 20 trees, so you should be able to see that the interval 6-10 is at least 6 x 20 = 120 and your answer must be bigger than this so it can't be 119.5.

Can you work out how many more squares you need to count for the complete area, and therefore how many trees are included?
Um I reallt don’t know 😬😬
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9 months ago
#8
(Original post by gcsesarehard9)
Um I reallt don’t know 😬😬
OK think about the block 6-10 first. Can you see where I found 6 blocks of 25 little squares to make 6 x 20 = 120 trees as an estimate? But there are more little squares than this in that rectangle aren't there? How many more squares?

And then think about the 4-6 block. You need to estimate 4.5-6 so how can you do this? (This is a bit harder!)
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#9
(Original post by davros)
OK think about the block 6-10 first. Can you see where I found 6 blocks of 25 little squares to make 6 x 20 = 120 trees as an estimate? But there are more little squares than this in that rectangle aren't there? How many more squares?

And then think about the 4-6 block. You need to estimate 4.5-6 so how can you do this? (This is a bit harder!)
There is 1/4 more squares 😅😅😅 I’m lost 😔
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9 months ago
#10
(Original post by gcsesarehard9)
There is 1/4 more squares 😅😅😅 I’m lost 😔
I would just leave things as whole squares at the moment until you can see where this is going

Can you see that above the 6 blocks of 5x5 little squares in the 6-10 interval, there is a small rectangle that is 2 little squares high and 10 little squares wide? So how many extra little squares are there in that rectangle?
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#11
(Original post by davros)
I would just leave things as whole squares at the moment until you can see where this is going

Can you see that above the 6 blocks of 5x5 little squares in the 6-10 interval, there is a small rectangle that is 2 little squares high and 10 little squares wide? So how many extra little squares are there in that rectangle?
There’s 20 more
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9 months ago
#12
(Original post by gcsesarehard9)
There’s 20 more
OK good - keep that figure of 20 squares to one side for the moment.

Now look at the interval from 4 to 6 on the graph. How many little squares wide is it? How many little squares high?
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#13
(Original post by davros)
OK good - keep that figure of 20 squares to one side for the moment.

Now look at the interval from 4 to 6 on the graph. How many little squares wide is it? How many little squares high?
8 squares high
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9 months ago
#14
(Original post by gcsesarehard9)
8 squares high
Yep - and 5 wide. So an interval of 2 works out at 40 little squares in the region 4-6.
.
We want to know about the interval from 4.5 to 6 which is a gap of 1.5.

If an interval of 2 contains 40 little squares, how many little squares are in an interval of 1?
And how many little squares are in an interval of 0.5?
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#15
20 little squares in an interval of 1
So there would be 10 in 0.5 right?
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9 months ago
#16
(Original post by gcsesarehard9)
20 little squares in an interval of 1
So there would be 10 in 0.5 right?
Sorry - you didn't quote me so I didn't see your response

Good, so in the interval 4.5 to 6 (width 1.5) there are going to be 20 + 10 = 30 little squares.

So if you think back to the beginning, we found:

6 x 25 little squares = 6 x 20 trees = 120 trees.
20 extra little squares on top
and now have 30 more little squares.

So we have another 20 + 30 = 50 little squares to add in total. But we know that 25 squares = 20 trees, so 50 squares = 2 x 20 = 40 trees.

So our total number of trees = 120 + 40 = 160 which is the answer you quoted
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#17
(Original post by davros)
Sorry - you didn't quote me so I didn't see your response

Good, so in the interval 4.5 to 6 (width 1.5) there are going to be 20 + 10 = 30 little squares.

So if you think back to the beginning, we found:

6 x 25 little squares = 6 x 20 trees = 120 trees.
20 extra little squares on top
and now have 30 more little squares.

So we have another 20 + 30 = 50 little squares to add in total. But we know that 25 squares = 20 trees, so 50 squares = 2 x 20 = 40 trees.

So our total number of trees = 120 + 40 = 160 which is the answer you quoted
Thank you so much for the help I really appreciate it!
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