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Real-Life Activities

Real-Life Math -- Solution

As its title suggests, technical illustration is a technical career. Illustrators must be able to take an object and break it down into diagrams that make sense to even the least technically inclined.

"A lot of companies ask me to illustrate representations of products that are impossible to photograph or work better as a diagram, where you can see how parts come together," says Chris Ceccarelli.

To accomplish that, you need good math skills.

You're consulting with Sandra in order to make a technical illustration of a new part she has designed.

You set a tolerance of plus or minus 1/64 of an inch for the machinists on the dimensions 2 1/4 x 3 1/2. What are the upper and lower limits of your tolerance?

Part A

Maximum acceptable size:

Max1 = 2 1/4 + 1/64
Max1 = 9/4 + 1/64

First you must handle the fractions so that you can add them together. To do that, multiply the first fraction by 16.

Max1 = 144/64 + 1/64
Max1 = 145/64
Max1 = 2 17/64
Max2 = 3 1/2 + 1/64
Max2 = 7/2 + 1/64
Max2 = 224/64 + 1/64
Max2 = 225/64
Max2 = 3 33/64

The maximum tolerance for this part is: 2 17/64 x 3 33/64 inches.

Minimum tolerance:

Min1 = 2 1/4 - 1/64
Min1 = 144/64 - 1/64
Min1 = 143/64
Min1 = 2 15/64
Min2 = 3 1/2 - 1/64
Min2 = 224/64 - 1/64
Min2 = 223/64
Min2 = 3 31/64

The minimum acceptable machined size of the part is 2 15/64 x 3 31/64 inches.

Part B

Another section of the part has a diameter of 4 inches. However, you need to know the circumference of this circle in order to draw it. What is the circumference?

Circumference = 3.14 x diameter

C = 3.14 x 4 inches
C = 12.56

You'll draw a circle with a circumference of 12.56 inches.