| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.31 |
| Score | 0% | 66% |
A machine in a factory has an error rate of 6 parts per 100. The machine normally runs 24 hours a day and produces 10 parts per hour. Yesterday the machine was shut down for 5 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 131 | |
| 141.1 | |
| 121 | |
| 178.6 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{6}{100} \) x 10 = \( \frac{6 \times 10}{100} \) = \( \frac{60}{100} \) = 0.6 errors per hour
So, in an average hour, the machine will produce 10 - 0.6 = 9.4 error free parts.
The machine ran for 24 - 5 = 19 hours yesterday so you would expect that 19 x 9.4 = 178.6 error free parts were produced yesterday.
Which of the following is an improper fraction?
\(1 {2 \over 5} \) |
|
\({a \over 5} \) |
|
\({7 \over 5} \) |
|
\({2 \over 5} \) |
A rational number (or fraction) is represented as a ratio between two integers, a and b, and has the form \({a \over b}\) where a is the numerator and b is the denominator. An improper fraction (\({5 \over 3} \)) has a numerator with a greater absolute value than the denominator and can be converted into a mixed number (\(1 {2 \over 3} \)) which has a whole number part and a fractional part.
A sports card collection contains football, baseball, and basketball cards. If the ratio of football to baseball cards is 9 to 2 and the ratio of baseball to basketball cards is 9 to 1, what is the ratio of football to basketball cards?
| 3:6 | |
| 9:8 | |
| 81:2 | |
| 7:8 |
The ratio of football cards to baseball cards is 9:2 and the ratio of baseball cards to basketball cards is 9:1. To solve this problem, we need the baseball card side of each ratio to be equal so we need to rewrite the ratios in terms of a common number of baseball cards. (Think of this like finding the common denominator when adding fractions.) The ratio of football to baseball cards can also be written as 81:18 and the ratio of baseball cards to basketball cards as 18:2. So, the ratio of football cards to basketball cards is football:baseball, baseball:basketball or 81:18, 18:2 which reduces to 81:2.
A menswear store is having a sale: "Buy one shirt at full price and get another shirt for 5% off." If Alex buys two shirts, each with a regular price of $13, how much money will he save?
| $1.95 | |
| $1.30 | |
| $3.25 | |
| $0.65 |
By buying two shirts, Alex will save $13 x \( \frac{5}{100} \) = \( \frac{$13 x 5}{100} \) = \( \frac{$65}{100} \) = $0.65 on the second shirt.
What is the distance in miles of a trip that takes 8 hours at an average speed of 45 miles per hour?
| 450 miles | |
| 360 miles | |
| 140 miles | |
| 135 miles |
Average speed in miles per hour is the number of miles traveled divided by the number of hours:
speed = \( \frac{\text{distance}}{\text{time}} \)Solving for distance:
distance = \( \text{speed} \times \text{time} \)
distance = \( 45mph \times 8h \)
360 miles