Situations to Expressions

Help Questions

ISEE Middle Level: Quantitative Reasoning › Situations to Expressions

Questions 1 - 10
1

Maria is y years old. Her brother, Sam, is 4 years younger. Their father is 1 year more than twice the sum of Maria's and Sam's ages. Which expression represents the father's age?

\(4y - 7\)

\(2(2y - 4)\)

\(4y - 3\)

\(3y - 3\)

Explanation

First, find the ages of Maria and Sam: Maria is y, Sam is y - 4. The sum of their ages is \(y + (y - 4) = 2y - 4\). Twice the sum of their ages is \(2(2y - 4) = 4y - 8\). The father is 1 year more than this, so his age is \((4y - 8) + 1 = 4y - 7\).

2

A student has taken n tests and has an average score of 88. On the next test, the student scores a 96. Which expression represents the student's new average score for all n+1 tests?

\(\frac{88 + 96}{2}\)

\(88 + \frac{96}{n+1}\)

\(\frac{88n + 96}{n + 1}\)

\(\frac{88n + 96}{n}\)

Explanation

The average is the total sum of scores divided by the number of tests. The sum of the scores for the first n tests is 88n. After scoring 96 on the next test, the new total sum is 88n + 96. The new number of tests is n + 1. Therefore, the new average is the new sum divided by the new number of tests: \(\frac{88n + 96}{n + 1}\).

3

To build a straight fence, a post is needed at the beginning and the end, and a post is needed every f feet in between. If a fence is to be built that is L feet long, and L is a multiple of f, which expression represents the number of posts required?

\(\frac{L}{f} - 1\)

\(\frac{L}{f} + 1\)

\(L \cdot f + 2\)

\(\frac{L}{f}\)

Explanation

A fence of length L with posts every f feet is divided into L/f sections. For example, a 24-foot fence with posts every 8 feet has 3 sections. The number of posts needed is one more than the number of sections, because there is a post at the start of each section plus one final post at the very end. Therefore, the number of posts is \(\frac{L}{f} + 1\).

4

Let k be the smallest of three consecutive even integers. Which expression represents the sum of these three integers?

\(k(k+2)(k+4)\)

\(3k + 6\)

\(3k\)

\(3k + 3\)

Explanation

If k is the smallest of three consecutive even integers, the next even integer is k + 2, and the one after that is k + 4. The sum of these three integers is \(k + (k + 2) + (k + 4)\). Combining like terms gives \(3k + 6\).

5

A baker sells cupcakes for $3 each and cookies for $2 each. The cost to make each cupcake is c dollars, and the cost to make each cookie is k dollars. On a given day, the baker sells 70 cupcakes and 120 cookies. Which expression represents the baker's total profit for that day?

\(70(3-c) + 120(2-k)\)

\(70(3) + 120(2)\)

\(450 - (c+k)\)

\(70c + 120k\)

Explanation

Profit is calculated as (Revenue - Cost). A more direct way is to find the profit per item and multiply by the number of items sold. The profit on one cupcake is \((3-c)\). The profit on one cookie is \((2-k)\). For 70 cupcakes, the profit is \(70(3-c)\). For 120 cookies, the profit is \(120(2-k)\). The total profit is the sum of the profit from cupcakes and cookies: \(70(3-c) + 120(2-k)\).

6

On a science test, a student earns 5 points for each correct answer, loses 2 points for each incorrect answer, and gets 0 points for unanswered questions. The test has 40 questions in total. If a student answers c questions correctly and i questions incorrectly, which expression represents the student's score?

\(5c + 2i\)

\(5c - 2(40 - c)\)

\(5c - 2i\)

\(5(c) - 2(40 - c - i)\)

Explanation

The student's score is based on the points gained from correct answers minus the points lost from incorrect answers. The points gained are 5c. The points lost are 2i. The total score is \(5c - 2i\). The total number of questions (40) is extra information not needed to write the expression for the score, as the number of unanswered questions does not affect the score.

7

A jar contains only dimes and quarters. Let d be the number of dimes. The number of quarters is 3 more than twice the number of dimes. Which expression represents the total value of the coins in the jar, in cents?

\(35d + 75\)

\(60d + 75\)

\(60d\)

\(3d + 3\)

Explanation

First, express the number of each coin in terms of d. Number of dimes = d. Number of quarters = 2d + 3. Next, find the value of each set of coins in cents. Value of dimes = 10d. Value of quarters = \(25(2d + 3) = 50d + 75\). The total value is the sum: \(10d + 50d + 75 = 60d + 75\).

8

The original price of a jacket is p dollars. It is on sale for 30% off. A sales tax of 7% is then applied to the discounted price. Which expression represents the final cost of the jacket?

\(0.77p\)

\(1.07(0.70p)\)

\(0.70(1.07p)\)

\(0.70p + 0.07\)

Explanation

First, calculate the discounted price. A 30% discount means the price is 70% of the original, so the discounted price is 0.70p. Next, calculate the 7% sales tax on this new price. An increase of 7% is equivalent to multiplying by 1.07. So, the final cost is \(1.07 \times(0.70p)\). Choice D is equivalent, but the order in A better reflects the sequence of operations described.

9

A class sells $s$ bracelets for $4 each at a fundraiser. How would you express the total earnings in this scenario?

$s+4$

$s/4$

$4s$

$4-s$

Explanation

This question tests middle school quantitative reasoning skills by translating situations into algebraic expressions. The core concept involves understanding how real-world quantitative data can be represented using variables and operations in mathematics. In this specific stimulus, the class sells s bracelets at $4 each, requiring us to find the total earnings from this fundraiser. Choice C is correct because it accurately models the situation by multiplying the number of bracelets sold (s) by the price per bracelet ($4), giving 4s. Choice A is incorrect because it adds 4 to s instead of multiplying, which would only increase the count by 4 rather than calculating total revenue. To help students, encourage practice in identifying key quantitative relationships and expressing them algebraically. Teach them to recognize when multiplication is needed (for repeated addition or rate problems) versus when simple addition or subtraction applies.

10

Jordan has $j$ dollars and buys a game for $15$ and a snack for $3$. How can the remaining balance be expressed algebraically?

$j-(15+3)$

$(j-15)+3$

$j+15+3$

$j-(15\cdot3)$

Explanation

This question tests middle school quantitative reasoning skills by translating situations into algebraic expressions. The core concept involves understanding how real-world quantitative data can be represented using variables and operations in mathematics. In this specific stimulus, Jordan starts with j dollars and makes two purchases: a game for $15 and a snack for $3, requiring us to find the remaining balance. Choice A is correct because it accurately models the situation by subtracting the total cost of both items (15+3 = $18) from the initial amount j, giving j-(15+3). Choice B is incorrect because it subtracts only the game cost first, then adds 3, which would increase rather than decrease the balance after the second purchase. To help students, encourage practice in identifying key quantitative relationships and expressing them algebraically. Teach them to group multiple expenses together before subtracting from the initial amount, and watch for the importance of proper parentheses usage.

Page 1 of 3