Question

name:
3 - 1 additional practice
leveled practice in 1 - 2, fill in the boxes to solve.

1. a school orchestra has 60 members. 20% of the members are percussionists. how many orchestra members are percussionists?

20%·60 players
the number of percussionists is
□% of 60
=□·60
=□ percussionists.

1. of 800 cars that drove on a street during a week, 0.75% exceeded the 25 miles per hour speed limit by more than 10 miles per hour. how many cars drove over 35 miles per hour?

the number of cars driving over 35 miles per hour is
□% of □
=□·800
=□ drivers

1. an item sells for $40. the sales tax on the item is 8%. what is the sales tax and total cost?
2. when a bush was first planted in a garden, it was 12 inches tall. after two weeks, it was 120% as tall as when it was first planted. how tall was the bush after the two weeks?
3. the number of students in the marching band this year is 125% as many as the number of students in the marching band last year. if there were 36 students in the marching band last year, how many students are in the marching band this year?
4. joel earns a commission of 5% on the audio equipment he sells, and the store keeps the rest. he sells a $750 amplifier.

a. how much commission does joel earn from the sale?
b. how much does the store keep?

1. nixon estimates it will take him 5 hours to finish an art project. it actually takes him 320% of the time estimated. how many hours did it take him to finish the project?
2. a contaminant is found in a solution at a level of \\( \frac { 3 } { 500 } \\% \\). what fraction of the solution is this?

Explanation:

Step1: Calculate sales tax

Sales tax = 8% of $40.
$8\%=\frac{8}{100}=0.08$.
So, sales tax = $0.08\times40 = 3.2$.

Step2: Calculate total cost

Total cost = cost of item + sales tax.
Total cost = $40+3.2 = 43.2$.

Step3: Calculate height of bush

The bush was 12 inches tall initially. After two weeks, it was 120% of the initial height.
$120\%=\frac{120}{100}=1.2$.
Height after two weeks = $1.2\times12 = 14.4$ inches.

Step4: Calculate number of students in marching band

Last year there were 36 students. This year it is 125% of last year.
$125\%=\frac{125}{100}=1.25$.
Number of students this year = $1.25\times36=45$.

Step5: Calculate Joel's commission (a)

Commission is 5% of $750.
$5\%=\frac{5}{100}=0.05$.
Commission = $0.05\times750 = 37.5$.

Step6: Calculate store's amount (b)

Store's amount = total sale - commission.
Store's amount = $750 - 37.5=712.5$.

Step7: Calculate time taken by Nixon

Estimated time is 5 hours. Actual time is 320% of estimated time.
$320\%=\frac{320}{100}=3.2$.
Actual time = $3.2\times5 = 16$ hours.

Step8: Calculate fraction of contaminant

Contaminant level is $\frac{3}{500}\%$.
$\frac{3}{500}\%=\frac{3}{500}\times\frac{1}{100}=\frac{3}{50000}$.

Answer:

1. Sales tax: $\$3.2$, Total cost: $\$43.2$
2. Bush height: $14.4$ inches
3. Marching band students: $45$
4. a. Commission: $\$37.5$, b. Store's amount: $\$712.5$
5. Nixon's time: $16$ hours
6. Contaminant fraction: $\frac{3}{50000}$