I believe what the problem means is that the height of the child, if he/she grows in height, the mesurements are equal to 1 ft, 2 ft, 3 ft, 4 ft, etc only. and no decimals or fractions in between. it is also said that a human stops growing at the age of 20 naturally, hence with this increment, a child can grow incredibly very tall.
Answer:
The population is expected to double in 36 years
Step-by-step explanation:
According to the the rule of 72,
A value is doubled if the product of the annual rate and number of years is 72,
Given,
The annual rate of interest = 2%
Let x be the time in years after 1965,
By the above statement,
The population will double if,
x × 2 = 72 ⇒ x = 36
Hence, the after 36 years since 1965 the population will be doubled,
i.e in 2001. ( ∵ 36 years after 1965 )
4x-6= x+6
4x= x + 12
5x= 12
X= 12/5
X= 2.5