The average height of a persimmon tree, a mango tree and a jackfruit tree is 6.2 m. The jackfruit tree is twice as tall as the mango tree and 1.4 m taller than the persimmon tree. Find the average height of the persimmon tree and the mango tree.
Total height of the persimmon tree, the mango tree and the jackfruit tree
= 3 x 6.2
= 18.6 m

Height of the mango tree = 1 u
Height of the jackfruit tree = 2 u
Height of the persimmon tree = 2 u - 1.4

Total height of the persimmon tree, the mango tree and the jackfruit tree
= 1 u + 2 u + 2 u - 1.4
= 5 u - 1.4

5 u - 1.4 = 18.6
5 u = 18.6 + 1.4
5 u = 20

1 u = 20 ÷ 5 = 4

Total height of the persimmon tree and the mango tree
= 1 u + 2 u - 1.4
= 3 u - 1.4
= 3 x 4 - 1.4
= 12 - 1.4
= 10.6 m

Average height of the persimmon tree and the mango tree
= 10.6 ÷ 2
= 5.3 m

Answer(s): 5.3 m