# Two alloys,A and B,are each made up of copper,zinc znd tin.In alloy A,the ratio of copper to zinc is 3:2 and the ratio of zinc to tin is 3:5.

Class: Form 1

Subject: Mathematics

Topic: Rates, Ratios, Proportions and Percentages

## Lesson Summary

Two alloys,A and B,are each made up of copper,zinc znd tin.In alloy A,the ratio of copper to zinc is 3:2 and the ratio of zinc to tin is 3:5.
a)Determine the ratio, copper:zinc:tin in alloy A.
b)The mass of alloy A is 250kg.Alloy B has the same mass as alloy A but the amount of copper is 30% less than that of alloy A,Calculate.
i)The mass of tin in alloy A
ii)The total mass of zinc and tin in alloy B.
c)Given that ratio of zinc to tin in alloy B is 3:8,determine the amount of tin in alloy B than in alloy A.

a)Determine the ratio, copper:zinc:tin in alloy A.
c : z :t Multiply as per the arrows

= copper : zinc : tin=9 : 6 : 10

b)The mass of alloy A is 250kg.Alloy B has the same mass as alloy A but the amount of copper is 30% less than that of alloy A,Calculate.
i)The mass of tin in alloy A
1025x250 = 100kg
ii)The total mass of zinc and tin in alloy B.
Mass of copper in alloy B is
Mass of cooper in A x 70%
=925x 250 = 90kg x 70% = 63 kg.
Mass of zinc and tin in B = mass of B – mass of copper in B
250kg - 63kg = 187 kg
c)Given that ratio of zinc to tin in alloy B is 3:8,determine the amount of tin in alloy B than in alloy A.
mass of tin in B =811x 187 = 136 kg
the difference of mass of tin B and in A = 136 -100 = 36 kg

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