| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.39 |
| Score | 0% | 68% |
A machine in a factory has an error rate of 4 parts per 100. The machine normally runs 24 hours a day and produces 7 parts per hour. Yesterday the machine was shut down for 8 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 174.6 | |
| 77.6 | |
| 87.3 | |
| 107.5 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{4}{100} \) x 7 = \( \frac{4 \times 7}{100} \) = \( \frac{28}{100} \) = 0.28 errors per hour
So, in an average hour, the machine will produce 7 - 0.28 = 6.72 error free parts.
The machine ran for 24 - 8 = 16 hours yesterday so you would expect that 16 x 6.72 = 107.5 error free parts were produced yesterday.
How many hours does it take a car to travel 110 miles at an average speed of 55 miles per hour?
| 7 hours | |
| 2 hours | |
| 1 hour | |
| 9 hours |
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 time:
time = \( \frac{\text{distance}}{\text{speed}} \)
time = \( \frac{110mi}{55mph} \)
2 hours
If a rectangle is twice as long as it is wide and has a perimeter of 18 meters, what is the area of the rectangle?
| 2 m2 | |
| 72 m2 | |
| 18 m2 | |
| 32 m2 |
The area of a rectangle is width (w) x height (h). In this problem we know that the rectangle is twice as long as it is wide so h = 2w. The perimeter of a rectangle is 2w + 2h and we know that the perimeter of this rectangle is 18 meters so the equation becomes: 2w + 2h = 18.
Putting these two equations together and solving for width (w):
2w + 2h = 18
w + h = \( \frac{18}{2} \)
w + h = 9
w = 9 - h
From the question we know that h = 2w so substituting 2w for h gives us:
w = 9 - 2w
3w = 9
w = \( \frac{9}{3} \)
w = 3
Since h = 2w that makes h = (2 x 3) = 6 and the area = h x w = 3 x 6 = 18 m2
Simplify \( \frac{24}{52} \).
| \( \frac{5}{11} \) | |
| \( \frac{6}{13} \) | |
| \( \frac{8}{15} \) | |
| \( \frac{2}{5} \) |
To simplify this fraction, first find the greatest common factor between them. The factors of 24 are [1, 2, 3, 4, 6, 8, 12, 24] and the factors of 52 are [1, 2, 4, 13, 26, 52]. They share 3 factors [1, 2, 4] making 4 their greatest common factor (GCF).
Next, divide both numerator and denominator by the GCF:
\( \frac{24}{52} \) = \( \frac{\frac{24}{4}}{\frac{52}{4}} \) = \( \frac{6}{13} \)
Which of the following is not an integer?
-1 |
|
\({1 \over 2}\) |
|
0 |
|
1 |
An integer is any whole number, including zero. An integer can be either positive or negative. Examples include -77, -1, 0, 55, 119.