Question

Gretchen is using an overhead projector to enlarge a drawing so she can make a poster. the original drawing measures 60 mm wide by 80 mm high. she moves the projector so that the width of the projected image is 300 mm. if the original drawing and the projected image are similar figures, what will be the height of the projected image? (a) 225 mm (b) 400 mm (c) 440 mm (d) 180 mm

Answer 1

Set this up as a proportion with width on top and height on bottom.  Our proportion would look this then: $\frac{w}{h}: \frac{60}{80} = \frac{300}{x}$.  Cross-multiply to get 60x = 24000.  Divide both sides by 60 to find that the height is 400