Answer:
1.5.1 : constant difference is 8
1.5.2: When there are 10 chairs stacked, it's 127 cm tall.
Explanation:
There is a linear relationship between the height of the stack and the number of chairs.
1 chair = 55 cm + 0 extra cm = 55cm
2 chairs = 55cm + 8cm = 63 cm
3 chairs = 55cm + 8(2)cm = 71 cm
4 chairs = 55cm + 8(3)cm = 79 cm
1.5.1 the constant difference between all the underlined numbers above is 8.
1.5.2 You could just keep calculating above until you get 127 cm. (Your teacher might not like that, but it's an option!)
You can find the equation & either solve for the number of chairs OR graph it.
So if we let C = the number of stacked chairs, our equation for H (height) would be:
H = 55 + 8(C-1)
If we substitute H = 127, solve for C.
127 = 55+ 8(c-1)
127 = 55+ 8c-8
127 = 47 + 8c
127 -47 = 8c
80 = 8c
10=c
When there are 10 chairs stacked, it's 127 cm tall.
Check that the answer works:
55 cm (1st chair) + 8*9 (8cm for each additional chair) = 55+ 72 = 127 cm