# Tutor profile: Justin K.

## Questions

### Subject: Geometry

The United States Golf Association specifies that a golf ball must be spherical in shape and be no less than 42.7mm in diameter. What is the required volume of the golf ball (round to the nearest tenths)?

The formula for the volume of a sphere is V = 4/3 * pi * r^3 where r is the radius of the sphere. Since the diameter is given, to find the radius, use the following formula for diameter (d = 2r) and manipulate the variable to solve for r (r = d/2). Plug in 42.7mm for d, and you get 21.35 mm. From there, use the volume formula and plug 21.35 mm for r, and you get 40764.5 mm^3 (cubed). Remember for volume you add the cubed exponent to the final answer since the question asked for volume.

### Subject: Basic Math

A recipe to serve six people calls for 2 1/4 cups of flour, 2/3 cups of sugar, and 1 tablespoon of vanilla extract. How much of each ingredient will you need if you make the recipe for three people?

The recipe is for six people, and 3 is one half of six, so you multiply each ingredient by 1/2 to get the amount of each ingredient, which is 1 1/8 cups of flour, 1/3 cups of sugar, and 1/2 tablespoon of vanilla extract.

### Subject: Algebra

Please draw line graph of the form y = 2x - 3

You start by looking at the y intercept form, which is -3. You plot (0, -3) on a coordinate plane. Then, you look at the slope, which is 2, so you start at (0, -3) and you go up 2 and across right to get coordinate (1, -2). Using a straight edge, draw a line through both points and extend the line in both directions.

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