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Q1. (a) An alloy contains by mass 50% copper, 27% zinc and the remainder nickel.

Brass contains copper and zinc in the ratio 33:17 by mass.

15 kg of the alloy and 25 kg of the brass are melted together to form a new alloy.

Determine the percentage by mass of EACH element in the final alloy. (8)

(b) Painter A can antifoul a fishing boat in 15 hours.

Painter B can antifoul the same fishing boat in 10 hours.

Painter A begins antifouling the boat and after a period of time painter B joins in and assists A to complete the job in a total of 9 hours.

Determine how long painter A was working on his own before being assisted by B. (8)