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Eight hundred insects were weighed, and the resulting measur [#permalink]
30 May 2019, 10:33

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Expert's post

Eight hundred insects were weighed, and the resulting measurements, in milligrams, are summarized in the boxplot below.

Attachment:

#GREexcercise Eight hundred insects were weighed.jpg [ 23.86 KiB | Viewed 8378 times ]

(a) What are the range, the three quartiles, and the interquartile range of the measurements? (b) If the 80th percentile of the measurements is 130 milligrams, about how many measurements are between 126 milligrams and 130 milligrams?

Re: Eight hundred insects were weighed, and the resulting measur [#permalink]
14 Jun 2019, 11:46

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Expert's post

Carcass wrote:

Eight hundred insects were weighed, and the resulting measurements, in milligrams, are summarized in the boxplot below.

Attachment:

The attachment #GREexcercise Eight hundred insects were weighed.jpg is no longer available

(a) What are the range, the three quartiles, and the interquartile range of the measurements? (b) If the 80th percentile of the measurements is 130 milligrams, about how many measurements are between 126 milligrams and 130 milligrams?

Math Review Question: 5 Page: 297 Difficulty: medium

(a) What are the range, the three quartiles, and the interquartile range of the measurements?

Attachment:

Eight hundred insects were weighed, and the resulting measurements1.png [ 12.69 KiB | Viewed 8225 times ]

Range = 146 - 105 = 41

Attachment:

Eight hundred insects were weighed, and the resulting measurements2.png [ 12.95 KiB | Viewed 8218 times ]

The three quartiles are: Q1 = 114, Q2 = 118, Q3 = 126

The interquartile range = (3rd quartile) - (1st quartile) = 126 - 114 = 12

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(b) If the 80th percentile of the measurements is 130 milligrams, about how many measurements are between 126 milligrams and 130 milligrams?

80th percentile of the measurements is 130 milligrams This means 80% of the measurements are LESS than 130 mg 80% of 800 = 640 So, 640 measurements are LESS than 130 mg

KEY CONCEPT: The 3rd quartile (Q3) is the same as the 75th percentile. Q3 = 126 So, 75% of the measurements are LESS than 126 mg 75% of 800 = 600 So, 60 measurements are LESS than 126 mg

We get:

Attachment:

Eight hundred insects were weighed, and the resulting measurements3.png [ 24.75 KiB | Viewed 8221 times ]

So, the number of measurements are BETWEEN 126 mg and 130 mg = 640 - 600 = 40

Cheers, Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com Sign up for my free GRE Question of the Dayemails

Re: Eight hundred insects were weighed, and the resulting measur [#permalink]
05 Oct 2019, 14:40

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For b)

You can also notice that 126 = 75th percentile (Q3) and 130 = 80th percentile (given in the question). So the difference between them (i.e. the numbers between them) is then equal to 5 percentiles and 5% of 800 = 40.

Re: Eight hundred insects were weighed, and the resulting measur [#permalink]
23 Jan 2020, 00:17

The answers to the questions:

The concept for the 2nd question is: The percentile refers to the percentage of people (or measurements) below a given value. For example, 80th percentile is 130 milligrams implies that: 80% of all measurements are lower than 130

Re: Eight hundred insects were weighed, and the resulting measur [#permalink]
27 May 2020, 05:39

I have posted a detailed video on YouTube which talks about all aspects of Box and Whisker Plot.

Hope it helps!

Carcass wrote:

Eight hundred insects were weighed, and the resulting measurements, in milligrams, are summarized in the boxplot below.

Attachment:

#GREexcercise Eight hundred insects were weighed.jpg

(a) What are the range, the three quartiles, and the interquartile range of the measurements? (b) If the 80th percentile of the measurements is 130 milligrams, about how many measurements are between 126 milligrams and 130 milligrams?