| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.78 |
| Score | 0% | 56% |
What is \( 4 \)\( \sqrt{63} \) + \( 8 \)\( \sqrt{7} \)
| 12\( \sqrt{441} \) | |
| 12\( \sqrt{63} \) | |
| 32\( \sqrt{9} \) | |
| 20\( \sqrt{7} \) |
To add these radicals together their radicands must be the same:
4\( \sqrt{63} \) + 8\( \sqrt{7} \)
4\( \sqrt{9 \times 7} \) + 8\( \sqrt{7} \)
4\( \sqrt{3^2 \times 7} \) + 8\( \sqrt{7} \)
(4)(3)\( \sqrt{7} \) + 8\( \sqrt{7} \)
12\( \sqrt{7} \) + 8\( \sqrt{7} \)
Now that the radicands are identical, you can add them together:
12\( \sqrt{7} \) + 8\( \sqrt{7} \)A circular logo is enlarged to fit the lid of a jar. The new diameter is 60% larger than the original. By what percentage has the area of the logo increased?
| 25% | |
| 20% | |
| 30% | |
| 15% |
The area of a circle is given by the formula A = πr2 where r is the radius of the circle. The radius of a circle is its diameter divided by two so A = π(\( \frac{d}{2} \))2. If the diameter of the logo increases by 60% the radius (and, consequently, the total area) increases by \( \frac{60\text{%}}{2} \) = 30%
What is 8z5 x 4z6?
| 12z30 | |
| 32z5 | |
| 12z11 | |
| 32z11 |
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:
8z5 x 4z6
(8 x 4)z(5 + 6)
32z11
Convert x-3 to remove the negative exponent.
| \( \frac{1}{x^3} \) | |
| \( \frac{1}{x^{-3}} \) | |
| \( \frac{-1}{x^{-3}} \) | |
| \( \frac{-1}{-3x^{3}} \) |
To convert a negative exponent to a positive exponent, calculate the positive exponent then take the reciprocal.
A machine in a factory has an error rate of 5 parts per 100. The machine normally runs 24 hours a day and produces 6 parts per hour. Yesterday the machine was shut down for 2 hours for maintenance.
How many error-free parts did the machine produce yesterday?
| 125.4 | |
| 114.7 | |
| 143.2 | |
| 194 |
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 6 = \( \frac{5 \times 6}{100} \) = \( \frac{30}{100} \) = 0.3 errors per hour
So, in an average hour, the machine will produce 6 - 0.3 = 5.7 error free parts.
The machine ran for 24 - 2 = 22 hours yesterday so you would expect that 22 x 5.7 = 125.4 error free parts were produced yesterday.