| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.28 |
| Score | 0% | 66% |
A machine in a factory has an error rate of 2 parts per 100. The machine normally runs 24 hours a day and produces 8 parts per hour. Yesterday the machine was shut down for 2 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 135.2 | |
| 98.7 | |
| 167.6 | |
| 172.5 |
The hourly error rate for this machine is the error rate in parts per 100 multiplied by the number of parts produced per hour:
\( \frac{2}{100} \) x 8 = \( \frac{2 \times 8}{100} \) = \( \frac{16}{100} \) = 0.16 errors per hour
So, in an average hour, the machine will produce 8 - 0.16 = 7.84 error free parts.
The machine ran for 24 - 2 = 22 hours yesterday so you would expect that 22 x 7.84 = 172.5 error free parts were produced yesterday.
What is \( \frac{7}{3} \) + \( \frac{6}{7} \)?
| 3\(\frac{4}{21}\) | |
| \( \frac{8}{13} \) | |
| 1 \( \frac{9}{21} \) | |
| 2 \( \frac{6}{13} \) |
To add 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 7 are [7, 14, 21, 28, 35, 42, 49, 56, 63, 70]. The first few multiples they share are [21, 42, 63, 84] making 21 the smallest multiple 3 and 7 share.
Next, convert the fractions so each denominator equals the lowest common multiple:
\( \frac{7 x 7}{3 x 7} \) + \( \frac{6 x 3}{7 x 3} \)
\( \frac{49}{21} \) + \( \frac{18}{21} \)
Now, because the fractions share a common denominator, you can add them:
\( \frac{49 + 18}{21} \) = \( \frac{67}{21} \) = 3\(\frac{4}{21}\)
Which of the following is a mixed number?
\({5 \over 7} \) |
|
\({a \over 5} \) |
|
\({7 \over 5} \) |
|
\(1 {2 \over 5} \) |
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.
What is the next number in this sequence: 1, 6, 11, 16, 21, __________ ?
| 26 | |
| 25 | |
| 35 | |
| 21 |
The equation for this sequence is:
an = an-1 + 5
where n is the term's order in the sequence, an is the value of the term, and an-1 is the value of the term before an. This makes the next number:
a6 = a5 + 5
a6 = 21 + 5
a6 = 26
Which of the following statements about exponents is false?
b1 = b |
|
all of these are false |
|
b0 = 1 |
|
b1 = 1 |
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).