Q:

How to estimate 5 percent breaking point  of  a sample of ropes?

The breaking strengths in pounds of five specimens of rope were 660, 460, 540, 580, and 550. 
How can I estimate the point at which only 5 percent of such specimens would be expected to break?

A:

What assumptions do you want to make? 
Rope is often composed of intertwined strings of material (say, hemp or some plastic fibre). The breaking strength of the rope can be assumed to be the sum of these fibres' individual breaking strengths. What does this tell you about the distribution of breaking strength in the rope?

