SAT Math: Percent 03

The atomic weight of a newly discovered element, in atomic mass units (amu), is approximately 60% less than that of potassium. The atomic weight of potassium is 39 amu. Which of the following best approximates the atomic weight, in amu, of the newly discovered element?

$16$

$30$

$23$

$36$

A camera normally costs $x$ dollars. It was marked down by 20%, but then marked up again by 30%. What is the final price of the camera?

$1.1x$

$1.5x$

$.24x$

$1.04x$

A newspaper has 70 slots available for advertisements. If 20% of the first 20 were sold in color, 30% of the next 40 were sold in color, and 50% of the last 10 were sold in color, what percent of the 70 ads were in color?

70%

21%

30%

46%

Kathy slices a cake into $x$ equal slices and eats one slice. In terms of $x$ , what percent of the cake is left?

$(x-1) \times 100 \%$

$\dfrac{x-1}{x} \%$

$\dfrac{x-1}{x} \times 100 \%$

$\dfrac{1}{x} \times 100 \%$

Joe has $b$ grams of blueberries, and use 20% of the blueberries to make smoothies, each of which require $s$ grams. The rest of the blueberries are used to make pies, each of which requires $p$ grams. Which of the following gives the number of pies Joe can make?

$\dfrac{4s}{5p}$

$\dfrac{4b}{5p}$

$\dfrac{s}{5p}$

$\dfrac{b}{5p}$

A leather jacket is selling for $440 after a 20% discount. What as the original selling price?

$352

$528

$550

$888