Fractions.

Question

There are 3 switches in a panel. Each switch is 2 1/2 inches wide , there is a clearance of 1 1/4 between switches and 3 7/8 between any switch an edge of the panel, how wide is the box? 

Answer 1

This I solve it as follows:

I will assume that the three switches are in a horizontal row.

3 switches, 3* (2(1/2)) = 7.5 inches

2 spaces 2*(1(1/4)) = 2.5 inches

2 sides  2*(3(7/8)) = (31/4)

Adding all this we get: (31/4) + (15/2) + (5/2) = (31/4) +(30/4) + (10/4) = 71/4 =

(17(3/4)) inches = 17.75 inches is the width of the box.