What is a possible expression that represents the ratio of the area of a circle to the circumference of a circle?
To solve this problem, we must first identify the expressions for the area and circumference of a circle and set up a ratio. The area of a circle is equal to pi*r^2 The circumference of a circle is equal to 2*pi*r. By dividing (pi*r^2)/(2*pi*r) and canceling terms that appear in the numerator and denominator, we find that the ratio is equal to r/2.
If you have .25 grams of water, how many moles do you have?
To find the number of moles, we must set up a proportion. We need the number of grams, which is given and the molecular weight of the substance we are working with, which is water. grams of water/molecular mass of water (grams/mol) = moles .25g H2O/18 (g/mol) = .01389 moles of Water
Jenny has x (an unknown number) of shirts in her closet. This is three more than four times the number of pairs of pants she has in her closet. How many pairs of pants does Jenny have in her closet?
We do not know the number of shirts or pairs of pants Jenny has, so we will choose variables for each. Let x represent the number of shirts and y represent the number of pairs of pants. We are asked to find y, the number of pants. Since x is three more than four times the number of y, we can set up an equation. x=4y+3. Therefore, y=(x-3)/4. The number of pants is not known, but we can set up an equation to find that number once we have the number of shirts.