posted by francis on .
tilissa was on the middle rung of a ladder.she went up 3 rungs,thendown 5 rungs and then up 7 rungs where she rested.later she climbed up the remaining 7 rungs on the ladder.how many rungs did the ladder have?
To have a middle rung, the number of rungs must be odd
e.g. if she is on rung #7, there would be 13 rungs
6 below her, and 6 above her, she is on #7
So assume she is on rung #x
so there are 2x-1 rungs
x+3 - 5 + 7 = 2x-1
-x = -6
x = 6
The ladder had 2(6) -1 or 11 rungs
she started at 6,
went up 3 , was on 9
went down 5, was on 4
went up 7, was on 11, the top rung
(Very dangerous to stand on the top rung of a ladder.)