After Riordan had stacked up 12 chairs in the tuckshop after a function, he noticed 3 things. Firstly, each of the chairs was stacked the same height above the other. Secondly, the foot of the fifth chair was 35.6 cm above that of the first. Thirdly, the chairs reached a height of 177.5 cm. What is the height of each chair?
Number of chairs that contributed to the height of 35.6 cm above the first chair
= 5 - 1
= 4

Height increase with each additional stacked chair
= 35.6 ÷ 4
= 8.9 cm

Number of chairs stacked on top of the first chair
= 12 - 1
= 11

Height increase of 11 additional stacked chairs
= 11 x 8.9
= 97.9 cm

Height of one chair
= 177.5 - 97.9
= 79.6 cm

Answer(s): 79.6 cm