Ratio, Proportion, Rates and Percentages

115.
The diagram shows two solid cones which are geometrically similar.
The height of the smaller cone is x cm and that of the larger one is 9 cm.
The volume of the smaller cone is 32 cm3 and the volume of the larger cone is 108 cm3.
Two similar cones
Calculate the value of x.
x = ......................... [3]
Paper 2
116.
In the triangle ABC, AB is parallel to DE.
Angle BAD = 110° and angle ACB = 36°.
Triangle ABC with DE parallel to AB
(a) Given that CE = 3 cm and EB = 2 units.
Calculate the ratio area of ABC area of DEC .
(a) ......................... [2]
Paper 2
117.
A box of fruit juice contains a mixture of apple, orange, pineapple and tropical juices.
The mixture is in the ratio apple : orange : pineapple : tropical = 9 : 7 : 4 : 5.
The box contains 540 millilitres of apple juice.
(a) Find the total amount of fruit juice in the box in litres.
(a) ......................... l [2]
(b) Calculate the amount of tropical juice in the box. Give your answer in millilitres.
(b) ......................... ml [2]
(c) 70% of the tropical juice is mango. Calculate the amount of mango juice in the box.
(c) ......................... ml [2]
Paper 2
118.
x : y = 3 : 7 and y : z = 2 : 3
Find the ratio x : y : z .
x : y : z = ......................... [2]
Paper 2
119.
The cubes A and B have volume of 216 cm3 and 64 cm3.
Two cubes A and B
Find the ratio:
(a) Height of A : height of B,
(a) ......................... [2]
(b) Surface area of A : surface area of B.
(b) ......................... [1]
Paper 2
120.
A farmer harvests 500 bags of corn every year.
He sells 2 5 of this harvest, keeps 48% as seed and keeps the remaining for his family.
Calculate the number of bags kept for the family.
......................... bags [3]
Paper 2
121.
P varies inversely as a square of r.
When p = 9, r = 2.
(a) Write an expression for p in terms of r.
(a) ......................... [2]
(b) Find the decrease in p if r is tripled.
(b) ......................... [3]
(c) v and w are two other quantities such that p is inversely proportional to v and v is inversely proportional to w.
Show that p is directly proportional to w.
(c) ......................... [2]
Paper 2
122.
t varies inversely as the difference of r2 and 7.
t = 9 when r = −2.
(a) Write an equation for t, in terms of r.
(a) ......................... [1]
(b) It is further given that t = 12 when r = a b , where a and b are integers.
Find the value of a and the value of b.
(b) a = ......................... b = ......................... [3]
Paper 2
123.
Khaola makes a map of Mafeteng and uses a scale of 1 : 50 000.
The area of a village on his map is 8 cm2.
Calculate, in square kilometres, the actual area of the village.
......................... km2 [2]
Paper 2
124.
(a) y is inversely proportional to x3.
When y = 9, x = 3.
Find y when x = 10.
(a) ......................... [2]
(b) p is proportional to q2.
Find the percentage increase in the value of p when q is increased by 50%.
(b) ......................... % [2]
Paper 2
125.
x is inversely proportional to (y − 2).
When y = 6, x = 9.
Find the value of x when y = 20.
x = ......................... [3]
Paper 2
126.
p is inversely proportional to q2.
Given that p = 24 for a particular value of q,
Find the value of p when q is doubled.
p = ......................... [3]
Paper 2
127.
Temperatures at 04 00 hours and 12 00 hours were −5°C and 19°C, respectively.
(a) Find the difference between the two temperatures.
(a) ......................... °C [1]
(b) Assuming that the temperature was rising at a steady rate, find:
(i) The temperature at 09 30 hours,
(b)(i) ......................... °C [3]
(ii) The time when the temperature was 8°C.
(b)(ii) ......................... hours [3]
Paper 2