Ratio and proportion
Q1. What should be subtracted from each of the numbers 9, 15 and 27 so that the resulting numbers are in the
continued proportion.
Q2. If a:b = c:d then prove that:
3 a+5 b
3 c+5 d
=
√
5 ma 2+7 n b2
2
5 mc +7 n d
2
Q3. If 12 is the mean proportional between two numbers and 96 is their third proportion, find the numbers.
Q4. Find two numbers such that the mean proportional between them is 18 and their third proportional is 144.
Q5. What number must be added to each of the number 6, 15, 20 and 43 to make them proportional.
1 1 3
Q6. If p + r = 3q and + = then prove that p:q = r:s
q s r
3 2
a +3 a b 63
Q7. Given that 3 2
= , using properties of proportion find the value of a:b.
b +3 a b 62
2 a−3 b−4 c+ 5 d 2 a−3 b+4 c−5 d
Q8. If = , then prove that 5ad = 6bc.
2 a+3 b−4 c −5 d 2a+ 3 b+4 c+ 5 d
Q9. Using properties of proportion find the value of x: If
√ 3 x + 4+ √ 3 x−5 =9.
√3 x +4− √3 x−5
2 2 3 3
x + y 41 x +y
Q10. If 2 2
= , using properties of proportion find (a) x:y , (b) 3 3
x −y 40 x −y
Q11. If x= 3
√3 a+1+ √3 a−1 , then prove that x3 – 3ax2 + 3x – a = 0.
√ a+1− √3 a−1
Q12. Using properties of proportion solve for x, given
√ 5 x + √ 2 x−6 =4.
√5 x− √2 x−6
3 3
x +12 x y +27 y
Q13. Using properties of proportion, find x:y if 2
= 2
6 x +8 9 y +27
4 2 2 4 2
a + a b +b a
Q14. If b is the mean proportional between a and c, show that 4 2 2 4
= 2
b +b c +c c
Q15. If x=
√ a+3 b+ √ a−3 b
, then prove that 3bx2 – 2ax + 3b = 0.
√ a+3 b− √ a−3 b
2 2
5 x −3 x +7 2 x + 4 x−5
Q16. Using properties of proportion solve for x, If =
3 x−7 −4 x+ 5
2 2
9 a +4 a−3 5 a −7 a+2
Q17 Using properties of proportion solve for x, If = .
4 a−3 −7 a+2