of 11 different babies are recorded on the line plot below

and we see there is one, two, three, four,

five, six, seven, eight, nine,

10, 11 data points.

Each one represents a different baby

whose weight is recorded.

Each weight was rounded to the nearest 1/8 of a pound.

All right, then they ask us,

what is the difference, in weight,

between the two heaviest babies?

So pause this video

and try to figure that out

before we work through it together.

All right, now where are the two heaviest babies?

So this one out here,

this is the heaviest baby,

and what is its weight?

Well, let's see.

Its weight is right over there,

and what is that number or what is that weight?

So this is nine and this is 10,

and we have one, two, three, four,

five, six, seven, eight equal spaces.

So each of these is an eighth.

So this is nine and one, two,

nine and 2/8.

So this one is, let me write this.

This is nine and 2/8.

Another way to think about it is,

2/8 is the same thing as 1/4,

'cause if you think about it,

it's one, two, three, four equal spaces.

This is also nine and 1/4 of the way to 10,

so this is the same thing as nine and 1/4.

And then what's the second heaviest babies?

'Cause we want the weight difference

between the two heaviest.

So the second heaviest baby is right over here

and we know that it is eight and a half pounds.

So what we really need to do is figure out

what is the difference between nine and 2/8

or nine and 1/4

and eight and a half right over here?

So we could set this up as a subtraction.

This is going to be nine and,

let's call it nine and 1/4,

minus, minus eight and a half,

and we can actually use this,

this, these measurement scales

or you can even view this as something

of a number line

to help us think about this.

The difference is this length right over here.

And we could think about it in terms of eighths,

'cause each of these hash marks is an eighth,

so 1/8, 2/8, 3/8, 4/8, 5/8 and 6/8.

So this is equal to 6/8.

We could also think about it in terms of fourths,

so this is 1/4, 2/4, and 3/4.

So this is equal to 3/4.

So what's the difference in weight

between the two heaviest babies?

It is 3/4 of a pound.