| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.72 |
| Score | 0% | 74% |
4! = ?
5 x 4 x 3 x 2 x 1 |
|
4 x 3 |
|
4 x 3 x 2 x 1 |
|
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 5c2 x 2c4?
| 10c2 | |
| 7c4 | |
| 7c8 | |
| 10c6 |
To multiply terms with exponents, the base of both exponents must be the same. In this case they are so multiply the coefficients and add the exponents:
5c2 x 2c4
(5 x 2)c(2 + 4)
10c6
What is the greatest common factor of 40 and 32?
| 15 | |
| 8 | |
| 13 | |
| 5 |
The factors of 40 are [1, 2, 4, 5, 8, 10, 20, 40] and the factors of 32 are [1, 2, 4, 8, 16, 32]. They share 4 factors [1, 2, 4, 8] making 8 the greatest factor 40 and 32 have in common.
Which of the following is a mixed number?
\({5 \over 7} \) |
|
\(1 {2 \over 5} \) |
|
\({7 \over 5} \) |
|
\({a \over 5} \) |
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 machine in a factory has an error rate of 8 parts per 100. The machine normally runs 24 hours a day and produces 8 parts per hour. Yesterday the machine was shut down for 5 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 139.8 | |
| 74.4 | |
| 119.7 | |
| 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 8 = \( \frac{8 \times 8}{100} \) = \( \frac{64}{100} \) = 0.64 errors per hour
So, in an average hour, the machine will produce 8 - 0.64 = 7.36 error free parts.
The machine ran for 24 - 5 = 19 hours yesterday so you would expect that 19 x 7.36 = 139.8 error free parts were produced yesterday.