Expert: Bobby Soltani - 5/4/2006

Question
Four holes are drilled in a straight line in a rectangular steel plate. The distance between hole 1 and hold 4 is 35 mm. The distance between hole 2 and hole 3 is the distance between hole 1 and 2. The distance between hole 3 and 4 is the same as the distance between hole 2 and 3. What is the distance, in millimeters between the center of hole 1 and the center of hole 3?

Answer
Hi Melissa,

Let the gap between 1 and 2 be x.
Let the gap between 2 and 3 be y.
Let the gap between 3 and 4 be z.

The distance between hole 1 and hold 4 is 35 mm.

x + y + z = 35

The distance between hole 2 and hole 3 is the distance between hole 1 and 2.

y = x

The distance between hole 3 and 4 is the same as the distance between hole 2 and 3.

z = y

What is the distance, in millimeters between the center of hole 1 and the center of hole 3? i.e. what is x + y?

x + y + z = 35

y = x, so we can put x in for y

x + x + z = 35

z = y, which equals x, so we can put x in for z also

x + x + x = 35

3x = 35

x = 11.67 mm

We want to know what is x + y

since y = x,

x + y = 11.67 + 11.67 = 23.33 mm.

Let me know if you have any questions.

Bobby