| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.44 |
| Score | 0% | 69% |
What is the greatest common factor of 80 and 40?
| 40 | |
| 20 | |
| 2 | |
| 32 |
The factors of 80 are [1, 2, 4, 5, 8, 10, 16, 20, 40, 80] and the factors of 40 are [1, 2, 4, 5, 8, 10, 20, 40]. They share 8 factors [1, 2, 4, 5, 8, 10, 20, 40] making 40 the greatest factor 80 and 40 have in common.
What is \( \frac{3}{9} \) - \( \frac{4}{15} \)?
| \(\frac{1}{15}\) | |
| \( \frac{6}{45} \) | |
| \( \frac{7}{12} \) | |
| 1 \( \frac{7}{12} \) |
To subtract these fractions, first find the lowest common multiple of their denominators. The first few multiples of 9 are [9, 18, 27, 36, 45, 54, 63, 72, 81, 90] and the first few multiples of 15 are [15, 30, 45, 60, 75, 90]. The first few multiples they share are [45, 90] making 45 the smallest multiple 9 and 15 share.
Next, convert the fractions so each denominator equals the lowest common multiple:
\( \frac{3 x 5}{9 x 5} \) - \( \frac{4 x 3}{15 x 3} \)
\( \frac{15}{45} \) - \( \frac{12}{45} \)
Now, because the fractions share a common denominator, you can subtract them:
\( \frac{15 - 12}{45} \) = \( \frac{3}{45} \) = \(\frac{1}{15}\)
A circular logo is enlarged to fit the lid of a jar. The new diameter is 45% larger than the original. By what percentage has the area of the logo increased?
| 35% | |
| 22\(\frac{1}{2}\)% | |
| 17\(\frac{1}{2}\)% | |
| 37\(\frac{1}{2}\)% |
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 45% the radius (and, consequently, the total area) increases by \( \frac{45\text{%}}{2} \) = 22\(\frac{1}{2}\)%
What is the next number in this sequence: 1, 8, 15, 22, 29, __________ ?
| 33 | |
| 36 | |
| 31 | |
| 43 |
The equation for this sequence is:
an = an-1 + 7
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 + 7
a6 = 29 + 7
a6 = 36
If \( \left|y - 1\right| \) - 9 = 3, which of these is a possible value for y?
| 13 | |
| 4 | |
| -7 | |
| -17 |
First, solve for \( \left|y - 1\right| \):
\( \left|y - 1\right| \) - 9 = 3
\( \left|y - 1\right| \) = 3 + 9
\( \left|y - 1\right| \) = 12
The value inside the absolute value brackets can be either positive or negative so (y - 1) must equal + 12 or -12 for \( \left|y - 1\right| \) to equal 12:
| y - 1 = 12 y = 12 + 1 y = 13 | y - 1 = -12 y = -12 + 1 y = -11 |
So, y = -11 or y = 13.