ISEE Upper Level Quantitative : ISEE Upper Level (grades 9-12) Quantitative Reasoning

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

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 : Greatest Common Factor

Column A               Column B

The GCF of             The GCF of

45 and 120             38 and 114

Possible Answers:

The quantities are equal.

There is not enough info to determine the relationship.

The quantity in Column B is greater.

The quantity in Column A is greater.

Correct answer:

The quantity in Column B is greater.

Explanation:

There are a couple different ways to find the GCF of a set of numbers. Sometimes it's easiest to make a factor tree for each number. The factors that the pair of numbers have in common are then multiplied to get the GCF. So for 45, the prime factorization ends up being: \(\displaystyle 5\cdot 3\cdot 3\). The prime factorization of 120 is: \(\displaystyle 5\cdot 3\cdot 2\cdot 2\cdot 2\). Since they have a 5 and 3 in common, those are multiplied together to get 15 for the GCF. Repeat the same process for 38 and 114. The prime factorization of 38 is \(\displaystyle 19\cdot 2\). The prime factorization of 114 is \(\displaystyle 19\cdot 3\cdot 2\). Therefore, multiply 19 and 2 to get 38 for their GCF. Column B is greater.

Example Question #1 : Numbers And Operations

What is the greatest common factor of \(\displaystyle 630\) and \(\displaystyle 660\)?

Possible Answers:

\(\displaystyle 30\)

\(\displaystyle 13860\)

\(\displaystyle 13860\)

\(\displaystyle 15\)

\(\displaystyle 60\)

Correct answer:

\(\displaystyle 30\)

Explanation:

To solve for the greatest common factor, it is necessary to get your numbers into prime factor form. For each of your numbers, this is:

\(\displaystyle 630 = 63 * 10 = 7 * 9 * 2 * 5 = 7 * 3 * 3 * 2 * 5\)

        \(\displaystyle = 2 * 3^2* 5*7\)

\(\displaystyle 660 = 66 * 10 = 6 * 11 * 2 * 5 = 2 * 3 * 11 * 2 *5\)

        \(\displaystyle = 2^2 *3*5*11\) 

Next, for each of your sets of prime factors, you need to choose the exponent for which you have the smallest value; therefore, for your values, you choose:

\(\displaystyle 2\)\(\displaystyle 2\)

\(\displaystyle 3\)\(\displaystyle 3\)

\(\displaystyle 5\)\(\displaystyle 5\)

\(\displaystyle 7\): None

\(\displaystyle 11\):  None

Taking these together, you get:

\(\displaystyle 2*3*5 = 30\)

 

Example Question #1 : Factors / Multiples

What is the greatest common factor of \(\displaystyle 520\) and \(\displaystyle 175\)?

Possible Answers:

\(\displaystyle 1820\)

\(\displaystyle 40\)

\(\displaystyle 5\)

\(\displaystyle 91\)

\(\displaystyle 3640\)

Correct answer:

\(\displaystyle 5\)

Explanation:

To solve for the greatest common factor, it is necessary to get your numbers into prime factor form. For each of your numbers, this is:

\(\displaystyle 520 = 52 * 10 = 13 * 4 * 2 * 5 = 13 * 2 * 2* 2 *5\)

        \(\displaystyle = 2^3 *5*13\)

\(\displaystyle 175 = 5 * 35 = 5 * 5 * 7 = 5^2 * 7\) 

Next, for each of your sets of prime factors, you need to choose the exponent for which you have the smallest value; therefore, for your values, you choose:

\(\displaystyle 2\): None

\(\displaystyle 5\)\(\displaystyle 5\)

\(\displaystyle 7\): None

\(\displaystyle 13\): None

Taking these together, you get: \(\displaystyle 5\)

Example Question #7 : Numbers And Operations

What is the greatest common factor of \(\displaystyle 208\) and \(\displaystyle 204\)?

Possible Answers:

\(\displaystyle 10608\)

\(\displaystyle 4\)

\(\displaystyle 429\)

\(\displaystyle 12\)

\(\displaystyle 5304\)

Correct answer:

\(\displaystyle 4\)

Explanation:

To solve for the greatest common factor, it is necessary to get your numbers into prime factor form. For each of your numbers, this is:

\(\displaystyle 208 = 4 * 52 = 2 * 2 * 4*13 = 2 * 2 * 2 * 2* 13\)

        \(\displaystyle =2^4 * 13\)

\(\displaystyle 204 = 6 * 34 = 2 * 3 * 2 * 17 = 2^2 * 3 * 17\) 

Next, for each of your sets of prime factors, you need to choose the exponent for which you have the smallest value; therefore, for your values, you choose:

\(\displaystyle 2\)\(\displaystyle 2^2\)

\(\displaystyle 3\): None

\(\displaystyle 13\): None

\(\displaystyle 17\): None

Taking these together, you get: \(\displaystyle 2^2 = 4\)

Example Question #1 : Greatest Common Factor

Annette's family has \(\displaystyle 8\frac{3}{5}\) jars of applesauce. In a month, they go through \(\displaystyle 4\frac{2}{3}\) jars of apple sauce. How many jars of applesauce remain?

Possible Answers:

\(\displaystyle 4\frac{14}{15}\)

\(\displaystyle 3\frac{14}{15}\)

\(\displaystyle 4\)

\(\displaystyle 3\frac{13}{15}\)

Correct answer:

\(\displaystyle 3\frac{14}{15}\)

Explanation:

If Annette's family has \(\displaystyle 8\frac{3}{5}\) jars of applesauce, and in a month, they go through \(\displaystyle 4\frac{2}{3}\) jars of apple sauce, that means \(\displaystyle 8\frac{3}{5}-4\frac{2}{3}\) jars of applesauce will be left. 

The first step to determining how much applesauce is left it to convert the fractions into mixed numbers. This gives us:

\(\displaystyle \frac{43}{5}-\frac{14}{3}\)

The next step is to find a common denominator, which would be 15. This gives us:

\(\displaystyle \frac{129}{15}-\frac{70}{15}\)

\(\displaystyle \frac{59}{15}\)

\(\displaystyle 3\frac{14}{15}\)

 

Example Question #2 : Greatest Common Factor

\(\displaystyle a\), \(\displaystyle b\), \(\displaystyle c\), \(\displaystyle d\), and \(\displaystyle e\) are five distinct prime integers. Give the greatest common factor of \(\displaystyle abc^{2}d\) and \(\displaystyle a^{2}bde^{2}\).

Possible Answers:

\(\displaystyle abcde\)

\(\displaystyle a^{2}b^{2}c^{2}d^{2}e^{2}\)

\(\displaystyle a^{2}bd\)

\(\displaystyle abd\)

\(\displaystyle a^{2}bc^{2}de^{2}\)

Correct answer:

\(\displaystyle abd\)

Explanation:

If two integers are broken down into their prime factorizations, their greatest common factor is the product of their common prime factors.

Since \(\displaystyle a\), \(\displaystyle b\), \(\displaystyle c\), \(\displaystyle d\), and \(\displaystyle e\) are distinct prime integers, the two expressions can be factored into their prime factorizations as follows - with their common prime factors underlined:

\(\displaystyle abc^{2}d = \underline{a} \cdot \underline{b} \cdot c \cdot c \cdot \underline{d}\)

\(\displaystyle a^{2}bde^{2} = \underline{a} \cdot a \cdot \underline{b} \cdot \underline{d} \cdot e \cdot e\)

The greatest common factor is the product of those three factors, or \(\displaystyle abd\).

Example Question #1 : Other Factors / Multiples

Which of these numbers is relatively prime with 18?

Possible Answers:

\(\displaystyle 35\)

\(\displaystyle 33\)

\(\displaystyle 32\)

\(\displaystyle 34\)

\(\displaystyle 39\)

Correct answer:

\(\displaystyle 35\)

Explanation:

For two numbers to be relatively prime, they cannot have any factor in common except for 1. The factors of 18 are 1, 2, 3, 6, 9, and 18.

We can eliminate 32 and 34, since each shares with 18 a factor of 2; we can also eliminate 33 and 39, since each shares with 18 a factor of 3. The factors of 35 are 1,  5, 7, and 35; as can be seen by comparing factors, 18 and 35 only have 1 as a factor, making 35 the correct choice.

 

Example Question #1 : How To Factor A Number

Which of the following is the prime factorization of 333?

Possible Answers:

333 cannot be factorized further

\(\displaystyle 3 \times 3 \times 37\)

\(\displaystyle 3 \times 111\)

\(\displaystyle 3 \times 11 \times 11\)

\(\displaystyle 3 \times 3\times3\times13\)

Correct answer:

\(\displaystyle 3 \times 3 \times 37\)

Explanation:

To find the prime factorization, break the number down as a product of factors, then keep doing this until all of the factors are prime.

\(\displaystyle 333 = 3 \times 111 = 3 \times3 \times 37\)

Example Question #2 : How To Factor A Number

Give the prime factorization of 91.

Possible Answers:

\(\displaystyle 91 = 7\times 13\)

91 is a prime number.

\(\displaystyle 91 = 3 \times 3 \times 17\)

\(\displaystyle 91 = 3 \times 3 \times 13\)

\(\displaystyle 91 = 7 \times 17\)

Correct answer:

\(\displaystyle 91 = 7\times 13\)

Explanation:

\(\displaystyle 91 = 7 \times 13\)

Both are prime factors so this is the prime factorization.

Example Question #11 : Factors / Multiples

How many factors does 40 have?

Possible Answers:

\(\displaystyle 9\)

\(\displaystyle 10\)

\(\displaystyle 6\)

\(\displaystyle 8\)

\(\displaystyle 7\)

Correct answer:

\(\displaystyle 8\)

Explanation:

40 has as its factors 1, 2, 4, 5, 8, 10, 20, and 40 - a total of eight factors.

Learning Tools by Varsity Tutors