Given, M₁ = 20 D₁ = 7, M₂ = 20 + 8 = 28
and D₂ = ?
Using formula, M₁D₁ = M₂D₂

Correct Option: B

Given, M₁ = 20 D₁ = 7, M₂ = 20 + 8 = 28
and D₂ = ?
Using formula, M₁D₁ = M₂D₂
⇒ 20 x 7 = 28 x D₂
∴ D₂ = (20 x 7)/28 = 5 days

Given, M₁ = 20, T₁ = 4, W₁ = 30,
M₂ = 20 - 4 = 16, T₂ = 12 and W₂ = ?
According to the formula,
M₁T₁W₂ = M₂T₂W₁

Correct Option: A

Given, M₁ = 20, T₁ = 4, W₁ = 30,
M₂ = 20 - 4 = 16, T₂ = 12 and W₂ = ?
According to the formula,
M₁T₁W₂ = M₂T₂W₁
⇒ 20 x 4 x W₂ = 16 x 12 x 30
∴ W₂ = (16 x 12 x 30)/(20 x 4) = 12 x 6 = 72 trees

Given, M₁ = 12, M₂ = 8 , D₁ = 24 , W₁ = 1, W₂ = 1
According to the formula,
M₁D₁W₂ = M₂D₂W₁

Correct Option: B

Given, M₁ = 12, M₂ = 8 , D₁ = 24 , W₁ = 1, W₂ = 1
According to the formula,
M₁D₁W₂ = M₂D₂W₁
⇒ 12 x 24 x 1= 8 x D₂ x 1
∴ D₂ = (12 x 24)/8
= 12 x 3 = 36 days

Given, M₁ = 40, W₁ = 200, T₁ = 8, D₁ = 12,
M₂ = 30, W₂ = 300, T₂ = 6 and D₂ = ?
Then, using formula
M₁T₁D₁W₂ = M₂T₂D₂W₁

Correct Option: A

Given, M₁ = 40, W₁ = 200, T₁ = 8, D₁ = 12,
M₂ = 30, W₂ = 300, T₂ = 6 and D₂ = ?
Then, using formula
M₁T₁D₁W₂ = M₂T₂D₂W₁
⇒ 40 x 8 x 12 x 300 = 30 x 6 x D₂ x 200
∴ D₂ = (40 x 8 x 12 x 300)/(30 x 6 x 200) = 32 days.

Here A = 60 days, B = 75 days, D = 30, T = ?
∴ Required time = (B - D) x [A/(A + B)]

Correct Option: C

Here A = 60 days, B = 75 days, D = 30, T = ?
∴ Required time = (B - D) x [A/(A + B)]
= (75 - 30) x [60/(60 + 75)]
= (45 x 60)/135 = 20 days
∴ Required time = 20 days