Need up to 30 seconds to load.

- [Instructor] The dot plot shows the

number of hours of daily driving time

for 14 school bus drivers.

Each dot represents a driver.

So for example, one driver drives one hour a day.

Two drivers drive two hours a day.

One driver drives three hours a day.

It looks like there's five drivers

that drive seven hours a day.

Which of the following is the closest

estimate to the percentile rank

for the driver with a daily driving time of six hours?

And then they give us some choices.

Which of the following is the closest estimate

to the percentile rank for the driver

with the daily driving time of six hours?

So pause the video and see if you can figure out

which of these percentiles is the closest estimate

to the percentile rank of a driver

with a daily driving time of six hours,

looking at this data right over here.

Alright, now let's work through this together.

So when you think about percentile

you really want to think about,

so let me write this down.

When we're talking about percentile

we're really saying the percentage

of the data

that,

and there's actually two ways that you could compute it.

One is the percentage of the data

that is below

the amount in question,

amount in question.

The other possibility is the percent

of the data

that is at or below,

that is at or below the amount,

the amount in question.

So if we look at this right over here,

let's just figure out how many data points,

what percentage of the data points

are below six hours per day.

So let's see, there are, I'm just gonna count 'em.

One, two, three, four, five, six, seven.

So seven of the 14 are below six hours.

So we could just say seven,

if we use this first technique

we would have seven of the 14 are below

six hours per day, and so that would

get us a number of 50%, that six hours

is at the 50th percentile.

If we want to say what percentage

is at that number or below then

we would also count this one, so we would say eight,

or eight out of 14.

Eight out of 14, which is the same thing

as four out of seven, and if we wanted

to write that as a decimal, let's see,

seven goes into four point zero zero zero,

we just need to estimate.

So seven goes into 40 five times.

35, we subtract, we get a five,

bring down a zero, it goes five times.

Look, it's just gonna be 0.5 repeating.

So 55.5555%.

So either of these would actually be

a legitimate response to the percentile rank

for the driver with the daily driving time of six hours.

It depends on whether you include the six hours or not.

So you could say either the 50th percentile

or roughly the 55th, or actually

the 56th percentile if you wanted

to round to the nearest percentile.

Now if you look at these choices here,

lucky for us there's only one choice

that's even, that's reasonably close

to either one of those, and that's the 55th percentile,

and it looks like the people who wrote this question

went with the calculation of percentile

where they include the data point in question.

So everything at six hours or less,

what percentage of the total data is that?