| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.19 |
| Score | 0% | 64% |
A machine in a factory has an error rate of 2 parts per 100. The machine normally runs 24 hours a day and produces 5 parts per hour. Yesterday the machine was shut down for 5 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 98.3 | |
| 140.1 | |
| 84.6 | |
| 93.1 |
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 5 = \( \frac{2 \times 5}{100} \) = \( \frac{10}{100} \) = 0.1 errors per hour
So, in an average hour, the machine will produce 5 - 0.1 = 4.9 error free parts.
The machine ran for 24 - 5 = 19 hours yesterday so you would expect that 19 x 4.9 = 93.1 error free parts were produced yesterday.
Convert 0.000285 to scientific notation.
| 2.85 x 10-5 | |
| 2.85 x 10-4 | |
| 0.285 x 10-3 | |
| 2.85 x 104 |
A number in scientific notation has the format 0.000 x 10exponent. To convert to scientific notation, move the decimal point to the right or the left until the number is a decimal between 1 and 10. The exponent of the 10 is the number of places you moved the decimal point and is positive if you moved the decimal point to the left and negative if you moved it to the right:
0.000285 in scientific notation is 2.85 x 10-4
What is the least common multiple of 3 and 11?
| 15 | |
| 14 | |
| 33 | |
| 22 |
The first few multiples of 3 are [3, 6, 9, 12, 15, 18, 21, 24, 27, 30] and the first few multiples of 11 are [11, 22, 33, 44, 55, 66, 77, 88, 99]. The first few multiples they share are [33, 66, 99] making 33 the smallest multiple 3 and 11 have in common.
This property states taht the order of addition or multiplication does not mater. For example, 2 + 5 and 5 + 2 are equivalent.
PEDMAS |
|
commutative |
|
distributive |
|
associative |
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.
22 members of a bridal party need transported to a wedding reception but there are only 4 5-passenger taxis available to take them. How many will need to find other transportation?
| 3 | |
| 6 | |
| 9 | |
| 2 |
There are 4 5-passenger taxis available so that's 4 x 5 = 20 total seats. There are 22 people needing transportation leaving 22 - 20 = 2 who will have to find other transportation.