| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.36 |
| Score | 0% | 67% |
Solve for \( \frac{2!}{6!} \)
| 504 | |
| 3024 | |
| \( \frac{1}{360} \) | |
| \( \frac{1}{60480} \) |
A factorial is the product of an integer and all the positive integers below it. To solve a fraction featuring factorials, expand the factorials and cancel out like numbers:
\( \frac{2!}{6!} \)
\( \frac{2 \times 1}{6 \times 5 \times 4 \times 3 \times 2 \times 1} \)
\( \frac{1}{6 \times 5 \times 4 \times 3} \)
\( \frac{1}{360} \)
What is \( \frac{4}{9} \) x \( \frac{1}{6} \)?
| \(\frac{4}{49}\) | |
| \(\frac{2}{3}\) | |
| \(\frac{1}{36}\) | |
| \(\frac{2}{27}\) |
To multiply fractions, multiply the numerators together and then multiply the denominators together:
\( \frac{4}{9} \) x \( \frac{1}{6} \) = \( \frac{4 x 1}{9 x 6} \) = \( \frac{4}{54} \) = \(\frac{2}{27}\)
A machine in a factory has an error rate of 8 parts per 100. The machine normally runs 24 hours a day and produces 9 parts per hour. Yesterday the machine was shut down for 2 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 146.9 | |
| 182.2 | |
| 101.9 | |
| 91.2 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{8}{100} \) x 9 = \( \frac{8 \times 9}{100} \) = \( \frac{72}{100} \) = 0.72 errors per hour
So, in an average hour, the machine will produce 9 - 0.72 = 8.28 error free parts.
The machine ran for 24 - 2 = 22 hours yesterday so you would expect that 22 x 8.28 = 182.2 error free parts were produced yesterday.
What is \( \frac{7}{3} \) - \( \frac{7}{11} \)?
| 1 \( \frac{2}{33} \) | |
| 1\(\frac{23}{33}\) | |
| 1 \( \frac{6}{33} \) | |
| 2 \( \frac{3}{33} \) |
To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 3 are [3, 6, 9, 12, 15, 18, 21, 24, 27, 30] and the first few multiples of 11 are [11, 22, 33, 44, 55, 66, 77, 88, 99]. The first few multiples they share are [33, 66, 99] making 33 the smallest multiple 3 and 11 share.
Next, convert the fractions so each denominator equals the lowest common multiple:
\( \frac{7 x 11}{3 x 11} \) - \( \frac{7 x 3}{11 x 3} \)
\( \frac{77}{33} \) - \( \frac{21}{33} \)
Now, because the fractions share a common denominator, you can subtract them:
\( \frac{77 - 21}{33} \) = \( \frac{56}{33} \) = 1\(\frac{23}{33}\)
What is the distance in miles of a trip that takes 2 hours at an average speed of 40 miles per hour?
| 360 miles | |
| 80 miles | |
| 55 miles | |
| 480 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 = \( 40mph \times 2h \)
80 miles