Given that,
p = 1058400, R = 5% and n = 2
According the formula,
Population n yr ago = P/(1 + R/100) ⁿ

Correct Option: C

Given that,
p = 1058400, R = 5% and n = 2
According the formula,
Population n yr ago = P/(1 + R/100) ⁿ
∴ Population 2yr ago = 1058400/(1+ 5/100)²
= 1058400 x 20/21 x 20/21 = 960000

Let the number of boys = B
and number of girls = G
Then, 10% of B = 1/4 of G

Correct Option: B

Let the number of boys = B
and number of girls = G
Then, 10% of B = 1/4 of G
⇒ B/10 = G/4
⇒ B/G = 10/4 = 5/2
⇒ B : G = 5 : 2

Population after 2 yr
= P (1 + R/100)²
= 250000 (1 + 2/100)²

Correct Option: D

Population after 2 yr
= P (1 + R/100)²
= 250000 (1 + 2/100)²
⇒ 250000 x (51/50) x (51/50) = 260100
∴ Growth = 260100 - 250000 = 10100

In such case, there is always decrease.
Given that, a = (common increase or decreased) = 7%

According to the formula,
Decreased Percentage = a²/100 %

Correct Option: D

In such case, there is always decrease.
Given that, a = (common increase or decreased) = 7%

According to the formula,
Decreased Percentage = a²/100 %
= 7²/100 %
= 0.49%

Given that,
P = 705600, R = 5% and n = 2

According to the formula,
Population after n yr = p(1 + R/100)ⁿ

Correct Option: A

Given that,
P = 705600, R = 5% and n = 2

According to the formula,
Population after n yr = p(1 + R/100)ⁿ

∴ Population after 2 yr.
= 705600 x (1+ 5/100)²
= 705600 x (105/100)²
= 705600 x (21/20 x 21/20) = 777924