| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.76 |
| Score | 0% | 55% |
What is \( \frac{4}{6} \) - \( \frac{7}{14} \)?
| 2 \( \frac{1}{4} \) | |
| \( \frac{2}{10} \) | |
| \( \frac{9}{42} \) | |
| \(\frac{1}{6}\) |
To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 6 are [6, 12, 18, 24, 30, 36, 42, 48, 54, 60] and the first few multiples of 14 are [14, 28, 42, 56, 70, 84, 98]. The first few multiples they share are [42, 84] making 42 the smallest multiple 6 and 14 share.
Next, convert the fractions so each denominator equals the lowest common multiple:
\( \frac{4 x 7}{6 x 7} \) - \( \frac{7 x 3}{14 x 3} \)
\( \frac{28}{42} \) - \( \frac{21}{42} \)
Now, because the fractions share a common denominator, you can subtract them:
\( \frac{28 - 21}{42} \) = \( \frac{7}{42} \) = \(\frac{1}{6}\)
A machine in a factory has an error rate of 5 parts per 100. The machine normally runs 24 hours a day and produces 9 parts per hour. Yesterday the machine was shut down for 8 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 83.3 | |
| 161.3 | |
| 136.8 | |
| 110.4 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{5}{100} \) x 9 = \( \frac{5 \times 9}{100} \) = \( \frac{45}{100} \) = 0.45 errors per hour
So, in an average hour, the machine will produce 9 - 0.45 = 8.55 error free parts.
The machine ran for 24 - 8 = 16 hours yesterday so you would expect that 16 x 8.55 = 136.8 error free parts were produced yesterday.
\({b + c \over a} = {b \over a} + {c \over a}\) defines which of the following?
commutative property for multiplication |
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distributive property for multiplication |
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distributive property for division |
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commutative property for division |
The distributive property for division helps in solving expressions like \({b + c \over a}\). It specifies that the result of dividing a fraction with multiple terms in the numerator and one term in the denominator can be obtained by dividing each term individually and then totaling the results: \({b + c \over a} = {b \over a} + {c \over a}\). For example, \({a^3 + 6a^2 \over a^2} = {a^3 \over a^2} + {6a^2 \over a^2} = a + 6\).
What is \( \frac{-5b^6}{8b^3} \)?
| -\(\frac{5}{8}\)b3 | |
| -1\(\frac{3}{5}\)b3 | |
| -\(\frac{5}{8}\)b9 | |
| -1\(\frac{3}{5}\)b-3 |
To divide terms with exponents, the base of both exponents must be the same. In this case they are so divide the coefficients and subtract the exponents:
\( \frac{-5b^6}{8b^3} \)
\( \frac{-5}{8} \) b(6 - 3)
-\(\frac{5}{8}\)b3
If a mayor is elected with 61% of the votes cast and 30% of a town's 47,000 voters cast a vote, how many votes did the mayor receive?
| 11,562 | |
| 7,755 | |
| 9,588 | |
| 8,601 |
If 30% of the town's 47,000 voters cast ballots the number of votes cast is:
(\( \frac{30}{100} \)) x 47,000 = \( \frac{1,410,000}{100} \) = 14,100
The mayor got 61% of the votes cast which is:
(\( \frac{61}{100} \)) x 14,100 = \( \frac{860,100}{100} \) = 8,601 votes.