Question

test prep

1. which expression has a value of 7?

a ( 4 + 0.5 \times 8 - 2 )
b ( (4 + 0.5) \times 8 - 2 )
c ( 4 + 0.5 \times (8 - 2) )
d ( (4 + 0.5) \times (8 - 2) )

1. chandra bought twice as many plants as marvin. kira bought ( \frac{1}{3} ) as many plants as chandra. marvin bought 6 plants. write an expression that shows the total number of plants purchased. who bought the most plants?
2. the art class lasts 90 minutes. the teacher explains the project for 25 minutes and allows 15 minutes for questions and discussion. he talks to each student about their project for 5 minutes and then all of the class time is used up. write and evaluate the expression that shows how many students are in the class.

spiral review

1. evaluate ( -3 - (-3 - 7) ).
2. evaluate ( \frac{\frac{5}{3} \times 1\frac{1}{5}}{\frac{1}{4}} ).
3. an account that yields 6% simple interest annually has $2,000. how much will be in the account after 3 years if no other deposits or withdrawals are made?
4. at the beginning of the month, sammi has saved $120 in her bank account. she wants to buy a new gaming system for $200 in three weeks. she earns $20 a week. will she have enough money at the end of three weeks to make the purchase? if not, how much more will she have to earn?

Explanation:

Question 7

Step1: Evaluate Option A

Using order of operations (PEMDAS: Parentheses, Exponents, Multiplication and Division, Addition and Subtraction), first multiply: \( 0.5 \times 8 = 4 \). Then add and subtract: \( 4 + 4 - 2 = 6 \).

Step2: Evaluate Option B

First, parentheses: \( (4 + 0.5) = 4.5 \). Then multiply: \( 4.5 \times 8 = 36 \). Then subtract: \( 36 - 2 = 34 \).

Step3: Evaluate Option C

Parentheses first: \( (8 - 2) = 6 \). Then multiply: \( 0.5 \times 6 = 3 \). Then add: \( 4 + 3 = 7 \).

Step4: Evaluate Option D

Parentheses: \( (4 + 0.5) = 4.5 \) and \( (8 - 2) = 6 \). Multiply: \( 4.5 \times 6 = 27 \).

Question 8

Step1: Find Chandra's plants

Marvin bought 6 plants. Chandra bought twice as many: \( 2 \times 6 = 12 \) plants.

Step2: Find Kira's plants

Kira bought \( \frac{1}{3} \) as many as Chandra: \( \frac{1}{3} \times 12 = 4 \) plants.

Step3: Total plants expression

Total plants = Marvin's + Chandra's + Kira's = \( 6 + 12 + 4 = 6 + 2 \times 6 + \frac{1}{3} \times (2 \times 6) \).

Step4: Compare quantities

Marvin: 6, Chandra: 12, Kira: 4. So Chandra has the most.

Question 9

Step1: Find remaining time for student talks

Total class time: 90 minutes. Explanation: 25 minutes, Q&A: 15 minutes. Remaining time: \( 90 - 25 - 15 = 50 \) minutes.

Step2: Calculate number of students

Time per student: 5 minutes. Number of students: \( 50 \div 5 = 10 \). So expression is \( (90 - 25 - 15) \div 5 \), and number of students is 10.

Question 10

Answer:

C. \( 4 + 0.5 \times (8 - 2) \)