Percentages
What is 25% of 200?
50
What is percent error?
The difference between the measured value and the true value, divided by the true value, expressed as a percentage.
What is percent change?
The difference between the new value and the old value, divided by the old value, expressed as a percentage.
What is measurement error?
The difference between the measured value and the true value.
How do divide fractions?
Look to the left, change the fraction on the left to its reciprocal, then multiply straight across.
If you scored 18 out of 30 on a test, what is your percentage score?
60%
If a measurement is 10 cm and the true value is 12 cm, what is the percent error?
16.67%
If the price of a book increases from $15 to $20, what is the percent change?
33.33%
If a thermometer reads 100°F but the actual temperature is 98°F, what is the measurement error?
2°F
A chef had to fill up 2⁄4 of a container with mashed potatoes. He ended up using 3 4⁄6 pounds of mashed potatoes. How many pounds would he use if he had to fill up the entire container?
7 4/12
Convert 0.75 to a percentage.
75%
Calculate the percent error if the estimated value is 50 and the actual value is 45.
10%
Calculate the percent change if a stock price drops from $50 to $40.
20%
The measurement of a cup of water is 50 mL. Mrs. Jensen estimated it to be 55 mL. What is her percent error?
10%
A carpenter goes through 3 1⁄6 boxes of nails finishing 3⁄4 of a roof. How much would he use finishing the entire roof?
4 4/18
A shirt costs $40, and it is on sale for 20% off. What is the sale price?
$32
What is the formula for calculating percent error?
Percent Error= (Measured- True) / (True) x 100
What is the formula to calculate percent change?
Percent Change=(New Value−Old Value) /Old Value×100
If a ruler is miscalibrated and reads 10 cm instead of the actual 12 cm, what is the measurement error?
2 cm
It takes 3 1⁄4 yards of thread to make 4 ⁄5 of a sock. How many yards of thread will it take to make an entire sock?
4 1/16
If a population of a town increases from 1,000 to 1,200, what is the percentage increase?
20%
If a student measures the length of a pencil as 6 cm but the actual length is 6.5 cm, what is the percent error? Round to the nearest hundredth.
7.69%
If a population decreases from 2,000 to 1,500, what is the percent change?
25%
A rectangular photograph is measured to be 8.5 inches in length. The actual length of the photograph, however, is 8.1 inches.
Approximately: 4.94%
Kira earned $7 mowing her neighbor's lawn for 1/2 of an hour. What is her hourly rate?
$14