Question

Bob climbed down a ladder from his roof, while Roy climbed up another ladder next to him. Each ladder had 30 rungs(steps). Their friend Jill recorded the following information about Bob and Roy: Bob went down 2 rungs every second. Roy went up 1 rung every second. At some point, Bob and Roy were at the same height. Which rung were they on?

Answer 1

Answer:

They were on 10th rung.

Step-by-step explanation:

Given,

The total rung( steps ) in the ladder = 30,

∵ Speed of Bob to coming down = 2 rung per second,

So, the height of bob after x seconds = 30 - 2x

Now, speed of Roy to climb the ladder = 1 rung per sec,

So, the height of Roy after x seconds = 1 × x = x

If x = 30 - 2x

x + 2x = 30

3x = 30

$\implies x =\frac{30}{3}=10$

Hence, they were be at 10th rung.