Question

test prep

1. which expression has a value of 7?

a 4 + 0.5 × 8 − 2
b (4 + 0.5) × 8 − 2
c 4 + 0.5 × (8 − 2)
d (4 + 0.5) × (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: Calculate Option A

Using order of operations (PEMDAS: Parentheses, Exponents, Multiplication and Division, Addition and Subtraction), first multiply: \(0.5\times8 = 4\). Then add and subtract: \(4 + 4 - 2 = 6\).

Step2: Calculate Option B

First, parentheses: \(4 + 0.5 = 4.5\). Then multiply: \(4.5\times8 = 36\). Then subtract: \(36 - 2 = 34\).

Step3: Calculate Option C

First, parentheses: \(8 - 2 = 6\). Then multiply: \(0.5\times6 = 3\). Then add: \(4 + 3 = 7\).

Step4: Calculate Option D

First, parentheses: \(4 + 0.5 = 4.5\) and \(8 - 2 = 6\). Then multiply: \(4.5\times6 = 27\).

Step1: Find Chandra's plants

Marvin bought 6 plants. Chandra bought twice as many: \(2\times6 = 12\) plants.

Step2: Find Kira's plants

Kira bought \(\frac{1}{3}\) as many as Chandra: \(\frac{1}{3}\times12 = 4\) plants.

Step3: Total plants expression

Total plants = Marvin's + Chandra's + Kira's = \(6 + 12 + 4\) or \(6 + 2\times6 + \frac{1}{3}\times(2\times6)\).

Step4: Compare quantities

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

Step1: Time used for non - student talk

Teacher explains for 25 minutes, questions/discussion for 15 minutes. Total non - student talk time: \(25 + 15 = 40\) minutes.

Step2: Time left for student talks

Class lasts 90 minutes. Time left for student talks: \(90 - 40 = 50\) minutes.

Step3: Number of students

Each student gets 5 minutes. Let \(n\) be the number of students. The expression is \(n=\frac{90-(25 + 15)}{5}\). Evaluate: \(\frac{90 - 40}{5}=\frac{50}{5}=10\).

Answer:

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

Question 8