| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.91 |
| Score | 0% | 58% |
A machine in a factory has an error rate of 6 parts per 100. The machine normally runs 24 hours a day and produces 6 parts per hour. Yesterday the machine was shut down for 7 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 103.7 | |
| 89.3 | |
| 110.4 | |
| 95.9 |
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 6 = \( \frac{6 \times 6}{100} \) = \( \frac{36}{100} \) = 0.36 errors per hour
So, in an average hour, the machine will produce 6 - 0.36 = 5.64 error free parts.
The machine ran for 24 - 7 = 17 hours yesterday so you would expect that 17 x 5.64 = 95.9 error free parts were produced yesterday.
What is \( \frac{1}{5} \) ÷ \( \frac{2}{5} \)?
| \(\frac{1}{2}\) | |
| \(\frac{1}{8}\) | |
| \(\frac{3}{10}\) | |
| 2\(\frac{1}{2}\) |
To divide fractions, invert the second fraction and then multiply:
\( \frac{1}{5} \) ÷ \( \frac{2}{5} \) = \( \frac{1}{5} \) x \( \frac{5}{2} \)
To multiply fractions, multiply the numerators together and then multiply the denominators together:
\( \frac{1}{5} \) x \( \frac{5}{2} \) = \( \frac{1 x 5}{5 x 2} \) = \( \frac{5}{10} \) = \(\frac{1}{2}\)
If \(\left|a\right| = 7\), which of the following best describes a?
none of these is correct |
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a = 7 |
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a = -7 |
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a = 7 or 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).
Which of the following statements about exponents is false?
b0 = 1 |
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b1 = b |
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b1 = 1 |
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all of these are false |
A number with an exponent (be) consists of a base (b) raised to a power (e). The exponent indicates the number of times that the base is multiplied by itself. A base with an exponent of 1 equals the base (b1 = b) and a base with an exponent of 0 equals 1 ( (b0 = 1).
This property states taht the order of addition or multiplication does not mater. For example, 2 + 5 and 5 + 2 are equivalent.
commutative |
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associative |
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distributive |
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PEDMAS |
The commutative property states that, when adding or multiplying numbers, the order in which they're added or multiplied does not matter. For example, 3 + 4 and 4 + 3 give the same result, as do 3 x 4 and 4 x 3.