Question

Please help me, I will give you a shiny medal :)

It deals with the midpoint and I'm not sure how to find the lower class limit from a frequency polygon :( because it only shows the midpoints of: lower class limit + next lower class limit /2

Answer 1

So i got all the questions before correct, but I'm not sure why the midpoint (lower) is not 20?

Answer 2

I thought since 15 was the actual second value (since -5 was just added to finish it) I thought, 15 is the second value? so.. since the class width is 10 I looked at the graph and found the half point in each part to put 10 for 'The lower limit of the second class' But I'm still not sure :(

Answer 3

wait is the other lower limit 10 as well? because 25-15 = 10 and 15-5 = 10?

Answer 4

I'm counting 11 classes. Not 10

Answer 5

Oh wait, the class from -5 to +5 doesn't make sense

Answer 6

Hmm but then again the ages 0,1,2,3,4,5 would be left out

Answer 7

yeah.. the -5 would be: values of -4, -3, -2, -1, 0, 1, 2, 3, 4, 5.. so a difference of 10... hmm i dont even know why they did that with age because age can't be negative?

Answer 8

we'd just ignore the negative values

Answer 9

I really don't like how they set this graph up. Anyways, I'm thinking the second class would be from 5 to 15

The midpoint is found by adding up those values and dividing by 2

Answer 10

so what would be the math behind the 15? because 5+15/2 = 10? I'm still confused :(

Answer 11

I'm not sure to be honest. If 15 was a midpoint, then the class would go from 5 to 25

but that would make the class width to be 20 (not 10)

Answer 12

I found another similar question example to the one I'm trying to figure out on this program but it didn't really explain anything much :/ maybe you might figure out the pattern... I thought it was just to half things..

Answer 13

oops this part got cut off "The upper class limit of a class is the largest value within the class. It is typically one less than the lower limit for the next class.
​Thus, the upper limit of the thirdthird class is 29."

Answer 14

How are they getting these values? The graph isn't matching up

Answer 15

Its what I was given when I clicked: assistance "example." :(

Answer 16

but what I did find was that :The upper class limit of a class is the largest value within the class. It is typically one less than the lower limit for the next class...

Answer 17

so is it 19? Because it should be one less than the next class? I dont even know if 20 is the next class beginning value >,<

Answer 18

oh I was reading the graph wrong. I know how to read it now

Answer 19

:DD how is it supposed to be read?

Answer 20

Every point except the first one (at -5) and the last one (at 105) represent midpoints of each class

The first midpoint is 5
the second is 15
the third is 25
etc

Answer 21

the class width is equal to the distance from any midpoint to the next one over

class width = 15 - 5 = 10
class width = 25 - 15 = 10
class width = 35 - 25 = 10
and so on...

Answer 22

each class is 10 units wide, so if we started at 10, then we must stop at 19

notice how 19-10+1 = 10

if we started at 20, then we must stop at 29 (not 30)

29-20+1 = 10

Answer 23

so the second class has a lower limit of 10 and an upper limit of 19

Answer 24

OOOH because 20 goes into the next class and we want to find the last number of the class distance before 20! so it's not a different of eleven but 10. But why did you add the one? what does it mean?

Answer 25

well let's say we want to know how many numbers are from 11 to 15

we subtract to get 15-11 = 4

but there's actually 5 values
11, 12, 13, 14, 15
and not 4. So that's why we add 1

Answer 26

Ohh! I see now! thank you so much for helping me! :D :)

Answer 27

sure thing