| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.04 |
| Score | 0% | 61% |
A machine in a factory has an error rate of 3 parts per 100. The machine normally runs 24 hours a day and produces 9 parts per hour. Yesterday the machine was shut down for 6 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 146.9 | |
| 157.1 | |
| 88.4 | |
| 209 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{3}{100} \) x 9 = \( \frac{3 \times 9}{100} \) = \( \frac{27}{100} \) = 0.27 errors per hour
So, in an average hour, the machine will produce 9 - 0.27 = 8.73 error free parts.
The machine ran for 24 - 6 = 18 hours yesterday so you would expect that 18 x 8.73 = 157.1 error free parts were produced yesterday.
If there were a total of 100 raffle tickets sold and you bought 3 tickets, what's the probability that you'll win the raffle?
| 6% | |
| 1% | |
| 3% | |
| 8% |
You have 3 out of the total of 100 raffle tickets sold so you have a (\( \frac{3}{100} \)) x 100 = \( \frac{3 \times 100}{100} \) = \( \frac{300}{100} \) = 3% chance to win the raffle.
4! = ?
3 x 2 x 1 |
|
4 x 3 x 2 x 1 |
|
4 x 3 |
|
5 x 4 x 3 x 2 x 1 |
A factorial has the form n! and is the product of the integer (n) and all the positive integers below it. For example, 5! = 5 x 4 x 3 x 2 x 1 = 120.
What is 9\( \sqrt{9} \) x 9\( \sqrt{2} \)?
| 81\( \sqrt{11} \) | |
| 243\( \sqrt{2} \) | |
| 81\( \sqrt{9} \) | |
| 18\( \sqrt{9} \) |
To multiply terms with radicals, multiply the coefficients and radicands separately:
9\( \sqrt{9} \) x 9\( \sqrt{2} \)
(9 x 9)\( \sqrt{9 \times 2} \)
81\( \sqrt{18} \)
Now we need to simplify the radical:
81\( \sqrt{18} \)
81\( \sqrt{2 \times 9} \)
81\( \sqrt{2 \times 3^2} \)
(81)(3)\( \sqrt{2} \)
243\( \sqrt{2} \)
If \(\left|a\right| = 7\), which of the following best describes a?
a = 7 |
|
a = 7 or a = -7 |
|
none of these is correct |
|
a = -7 |
The absolute value is the positive magnitude of a particular number or variable and is indicated by two vertical lines: \(\left|-5\right| = 5\). In the case of a variable absolute value (\(\left|a\right| = 5\)) the value of a can be either positive or negative (a = -5 or a = 5).