PSLE Eva hung some identical oval rings vertically. The thickness of each oval ring was 1 cm. The figure shows how the oval rings are connected.
- What was the distance from the top of the 1st oval ring to the bottom of the 4th oval ring?
- The distance from the top of the 1st ring to the bottom of the last ring was 153 cm. How many oval rings did Eva hang altogether?
(a)
Distance of 1 oval ring = 9 cm = 1 x 8 + 1
Distance of 2 oval rings = 17 cm = 2 x 8 + 1
Distance of 3 oval rings = 25 cm = 3 x 8 + 1
Distance from the top of the 1st oval ring to the bottom of the 4th oval ring = 25 cm
(b)
Formula
Distance from the top of the 1st oval ring to the bottom of the last oval ring = Number of oval rings x 8 + 1
Number of oval rings x 8 + 1 = 153
Number of oval rings x 8 = 153 - 1
Number of oval rings x 8 = 152
Number of oval rings = 152 ÷ 8
Number of oval rings = 19
Number of oval rings that Eva hung altogether = 19
Answer(s): (a) 25 cm; (b) 19