ISEE Middle Level Quantitative : ISEE Middle Level (grades 7-8) Quantitative Reasoning

Study concepts, example questions & explanations for ISEE Middle Level Quantitative

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Example Questions

Example Question #1 : How To Find Median

Consider the data set \(\displaystyle \left \{ 20, 30, 30, 40, 40, 40, 40, 50, 50, 60, \square \right \}\).

Which of the following elements, when plugged in for the square, make 40 the median of the data set?

Possible Answers:

All of the other responses are correct.

\(\displaystyle 10\)

\(\displaystyle 40\)

\(\displaystyle 60\)

\(\displaystyle 70\)

Correct answer:

All of the other responses are correct.

Explanation:

The median of eleven elements is the element in the middle, assuming the numbers are arranged in order.

If the box is replaced with a 40, the data set becomes

\(\displaystyle \left \{ 20, 30, 30, 40, 40, 40,40, 40, 50, 50, 60 \right \}\),

making 40 the sixth element.

If the box is replaced with a value less than 40, then the lowest five values are 20, 30, 30, 40, and the median is 40.

If the box is replaced with a value greater than 40, then the lowest five values are 20, 30, 30, 40, 40, and the median is 40.

No matter what, the median is 40.

 

 

Example Question #8 : How To Find Median

The six students in the science club weigh \(\displaystyle 145\) pounds, \(\displaystyle 172\) pounds, \(\displaystyle 166\) pounds, \(\displaystyle 159\) pounds, \(\displaystyle 153\) pounds, and \(\displaystyle 201\) pounds. Give the median of their weights.

Possible Answers:

\(\displaystyle 162.5 \textrm{ lbs}\)

\(\displaystyle 173\textrm{ lbs}\)

\(\displaystyle \textrm{160 lbs}\)

\(\displaystyle 166\textrm{ lbs}\)

\(\displaystyle 153 \textrm{ lbs}\)

Correct answer:

\(\displaystyle 162.5 \textrm{ lbs}\)

Explanation:

In ascending order, their weights are:

\(\displaystyle \left \{ 145, 153, 159,166, 172, 201\right \}\)

The median is the average of the two numbers in the middle of the set, which are \(\displaystyle 159\) and \(\displaystyle 166\):

\(\displaystyle \frac{159 + 166}{2} = \frac{325}{2} = 162.5\)

The median weight is \(\displaystyle 162.5\) pounds.

Example Question #121 : Statistics & Probability

Give the median of the following eight scores: 

\(\displaystyle \left \{ 61, 67, 80, 72, 76, 73, 90, 68 \right \}\)

Possible Answers:

\(\displaystyle 75.5\)

\(\displaystyle 72\)

\(\displaystyle 73\)

\(\displaystyle 73.375\)

\(\displaystyle 72.5\)

Correct answer:

\(\displaystyle 72.5\)

Explanation:

Arrange the scores from least to greatest.

\(\displaystyle \left \{ 61, 67, 68, 72, 73, 76, 80, 90 \right \}\)

There are an even number (eight) of scores, so the median is the arithmetic mean of the middle two scores, 72 and 73. This makes the median

\(\displaystyle \frac{72 + 73}{2} = 72.5\)

Example Question #1 : How To Find Median

Find the median of this set of numbers:

753, 159, 456, 654, 852, 963, 741.

 

Possible Answers:

\(\displaystyle 741\)

\(\displaystyle 804\)

\(\displaystyle 654\)

\(\displaystyle 753\)

\(\displaystyle 456\)

Correct answer:

\(\displaystyle 741\)

Explanation:

First, order the numbers from least to greatest.

\(\displaystyle 159, 456, 654, 741, 753, 852, 963\)

Then, identify the middle number: \(\displaystyle 741.\)

 

 

 

Example Question #11 : How To Find Median

Find the median of this set of numbers:

60, 74, 51, 43, 91,62, 65

Possible Answers:

\(\displaystyle 60\)

\(\displaystyle 64\)

\(\displaystyle 48\)

\(\displaystyle 65\)

\(\displaystyle 62\)

Correct answer:

\(\displaystyle 62\)

Explanation:

First, place the numbers in order from least to greatest:

\(\displaystyle 43, 51,60,62,65,74,91\)

Then, identify the middle number: 62.

 

Example Question #331 : Isee Middle Level (Grades 7 8) Quantitative Reasoning

Give the median of the following nine scores: 

\(\displaystyle \left \{ 61, 67, 80, 72, 76, 73, 90, 68, 70 \right \}\)

Possible Answers:

\(\displaystyle 75.5\)

\(\displaystyle 72\)

\(\displaystyle 73\)

\(\displaystyle 72.5\)

\(\displaystyle 68\)

Correct answer:

\(\displaystyle 72\)

Explanation:

Arrange the scores from least to greatest.

\(\displaystyle \left \{ 61, 67, 68, 70, 72, 73, 76, 80, 90 \right \}\)

There are an odd number (nine) of scores, so the median of the scores is the one that falls in the center - namely, 72.

Example Question #1 : Find Median

What is the median of the following set of numbers:

 

\(\displaystyle 1, 1,1,4,7,11,23,24,24\)

Possible Answers:

\(\displaystyle 15\)

No number is the median for this set of numbers

\(\displaystyle 7\)

\(\displaystyle 1\)

\(\displaystyle 10\)

Correct answer:

\(\displaystyle 7\)

Explanation:

The median is the number with an equal number of other items both above and below it.  There are 9 total numbers in the list, 4 of them are below 7, and 4 of them are above 7.

Example Question #113 : Data Analysis

What is the median of the values \(\displaystyle 55\), \(\displaystyle 90\), \(\displaystyle 33\), \(\displaystyle 78\), \(\displaystyle 46\)?

Possible Answers:

\(\displaystyle 302\)

\(\displaystyle 90\)

\(\displaystyle 60.4\)

\(\displaystyle 46\)

\(\displaystyle 55\)

Correct answer:

\(\displaystyle 55\)

Explanation:

The median of a set of values is the value that is in the middle when you rearrange the values from least to greatest. In this set, the values can be rearranged as \(\displaystyle 33\)\(\displaystyle 46\)\(\displaystyle 55\)\(\displaystyle 78\)\(\displaystyle 90\) and the median is \(\displaystyle 55\).

Example Question #82 : Data Analysis

On a math test that the teacher gave her students, the scores were as follows:

\(\displaystyle 77, 90, 91, 93, 75, 89, 71\)

What was the median score?

Possible Answers:

\(\displaystyle 78\)

\(\displaystyle 90\)

\(\displaystyle 91\)

\(\displaystyle 89\)

\(\displaystyle 77\)

Correct answer:

\(\displaystyle 89\)

Explanation:

The median is the middle number in a set when the set of numbers is ordered sequentially. 

When the intial set is reordered sequentially, you get the bottom set. (The top set is the original ordering of the numbers.)

\(\displaystyle 77, 90, 91, 93, 75, 89, 71\)

\(\displaystyle 71, 75, 77, 89, 90, 91, 93\)

In this sequential set of 7 numbers, the number 89 is in the fourth posiiton and exactly in the middle. Therefore, it is the mean. 

Example Question #2 : How To Find Median

What is the median of this set of numbers?

\(\displaystyle 89, 57, 34, 88, 22\)

Possible Answers:

\(\displaystyle 57\)

\(\displaystyle 34\)

\(\displaystyle 89\)

\(\displaystyle 22\)

\(\displaystyle 88\)

Correct answer:

\(\displaystyle 57\)

Explanation:

To find the median of a set of numbers, you must first reorder them from smallest to largest. Below is the set reordered as such:

\(\displaystyle 22, 34, 57, 88, 89\)

The median is the middle number of the set. Here, 57 is the middle number. Therefore, it is the median and the correct answer. 

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