Question

11. The heights of three plants A, B and C in a garden are in the ratio 2 : 3:5. Their mean height is
30 cm.
(a) Find the height of plant B.
(b) If another plant D is added to the garden and the mean height of the four plants is now 33 cm,
find the height of plant D.
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Answer 1

Step-by-step explanation:

Let A=2x,B=3x,C=5x.

Mean height=2x+3x+5x/3

30=10x/3

30 × 3=10x

90=10x

x=90/10

x=9

Height of plant B=3x

=3(9)

=27 cm

If another plant D is added to the garden mean height of the four plant is 33 cm.

Mean height=2x+3x+5x+plant D/4

33=10x+plant D/4

33=10(9)+plant D/4

33=90+plant D/4

33 × 4=90+plant D

132-90= plant D

plant D= 42 cm

Height of plant D is 42 cm.

Answer 2

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