Question

Lester ordered a book for $35; he must pay a shipping charge of 12%. Show how to find 12% of 35 by using benchmark percents, then find the amount of the shipping charge. Show your work.

a) Find 10% of 35 and then add 2% to it.
b) Find 20% of 35 and then subtract 8% from it.
c) Find 15% of 35 and then add 3% to it.
d) Find 25% of 35 and then subtract 13% from it.

Answer 1

To find 12% of $35, benchmark percents such as 10%, 20%, and 25% are used with adjustments. Methods a), b), and d) all reach the correct shipping charge of $4.20, while method c) is not valid for finding 12%.

Step-by-step explanation:

To find the shipping charge of a $35 book with a 12% fee, you can use benchmark percents. Here are the different methods you could use:

1. Find 10% of $35 by moving the decimal one place to the left, which gives you $3.50. Finding 2% involves cutting the 10% value in half and then dividing by 5. So, $3.50 / 2 = $1.75, and $1.75 / 5 = $0.35. Adding the 10% to the 2%, you get $3.50 + $0.35 = $4.20 for shipping.
2. Find 20% of $35 by doubling the 10% value. $3.50 * 2 = $7.00. To get 8%, halve the 10% value to find 5% ($1.75), and then find 1% ($0.35) by dividing the 10% value by 10, and multiply by 3 to get 3%. $0.35 * 3 = $1.05. Then add the 5% and 3% values to get 8%, which is $1.75 + $1.05 = $2.80. Subtract this from 20%, so $7.00 - $2.80 = $4.20 for shipping.
3. Find 15% of $35 by taking 10% ($3.50) and adding half of it (5%) which is $1.75. So, 15% is $3.50 + $1.75 = $5.25. To add 3%, find 1% of $35, which is $0.35 and multiply by 3 to get $1.05. Add this to 15%, so $5.25 + $1.05 = $6.30, which is not the correct way to find 12%.
4. Find 25% of $35, which is like finding a quarter of it. $35 divided by 4 equals $8.75. To subtract 13%, find 10% ($3.50) and 3% by finding 1% and multiplying by 3 ($0.35 * 3 = $1.05), and add them together to get $3.50 + $1.05 = $4.55. Subtraction from 25% yields $8.75 - $4.55 = $4.20 for shipping.

Of the choices given, a), b), and d) all correctly identify that to find 12% of $35, the best methods are a) Find 10% of 35 and add 2% to it, b) Find 20% of 35 and subtract 8% from it, and d) Find 25% of 35 and subtract 13% from it to get $4.20 as the shipping charge.

Answer 2

Lester ordered a book for $35; he must pay a shipping charge of 12%, the shipping charge of a book priced at $35 with a 12% rate is a) Find 10% of 35 and then add 2% to it.

Step-by-step explanation:

To find 12% of $35, you can use benchmark percents. Let's go through the options a), b), c), and d) to find the correct answer:

a) Find 10% of $35: $35 x 0.10 = $3.50.

Then add 2% to it: $3.50 + ($3.50 x 0.02) = $3.50 + $0.07 = $3.57.

So, the shipping charge would be $3.57.

b) Find 20% of $35: $35 x 0.20 = $7.

Then, subtract 8% from it: $7 - ($7 x 0.08) = $7 - $0.56 = $6.44.

This is not the correct answer.

c) Find 15% of $35: $35 x 0.15 = $5.25.

Then, add 3% to it: $5.25 + ($5.25 x 0.03) = $5.25 + $0.16 = $5.41.

This is not the correct answer.

d) Find 25% of $35: $35 x 0.25 = $8.75.

Then, subtract 13% from it: $8.75 - ($8.75 x 0.13) = $8.75 - $1.14 = $7.61.

This is not the correct answer.

Therefore, the correct answer is option a) Find 10% of $35 and then add 2% to it, which results in a shipping charge of $3.57.