The tensile strengths, measured in newtons (N), of a large number of ropes of equal length are independently and normally distributed such that 5% are under 706 N and 5% over 1294 N. Four such ropes are randomly selected and joined end-to-end to form a single rope; the strength of the combined rope is equal to the strength of the weakest of the 4 selected ropes. Derive the probabilities that this combined rope will not break under tensions of 1000 N and 900 N, respectively. A further 4 ropes are randomly selected and attached between two rings, the strength of the arrangement being the sum of the strengths of the 4 separate ropes. Derive the probabilities that this arrangement will break under tensions of 4000 N and 4200 N, respectively. (NEAB)