Q# 3,4. If x is directly proportional to y and x=4.5 when y=3, find an equation connected x and y

 

3. If x is directly proportional to Y and x=4.5 when Y=3 find

i) the equation connecting X and Y

X ∝ Y    (∝ symbol of directly Proportion)

X = KY (Where K is constant)

 

.: the value of K

4.5 = K3

K = 4.5÷3

K = 1.5

Connecting Equation is

X= 1.5Y

 

ii) the value of X when Y = 6

X = 1.5Y

X = 1.5 × 6

X = 9

 

III) the value of Y when X=12

X = 1.5Y

12 = 1.5 × Y

Y = 12/1.5

Y = 8

 

4. If Q is directly proportional to P and Q=28 when P=4

i) express Q in terms of p

Q ∝ P  (∝ symbol of directly Proportion)

Q = KP (Where K is constant)

 the value of K

28 = K × 4

K = 28 ÷ 4

K = 7

the equation is

Q = 7P

ii) find the value of Q when P=5

Q = 7P

Q = 7 × 5

Q = 35

iii) calculate the value of P=42

Q = 7P

42 = 7P

P = 42 ÷ 7

P = 6