Work Done by Three People Cutting Wood

Let $A, B, C$ be the rate of work per minute of Anand, Bharat, and Chandra respectively to cut 5 kg of wood.

$A + B = \frac{1}{20}$ $B + C = \frac{1}{40}$ $C + A = \frac{1}{30}$

Adding all three equations: $2(A + B + C) = \frac{1}{20} + \frac{1}{40} + \frac{1}{30} = \frac{6 + 3 + 4}{120} = \frac{13}{120}$ $A + B + C = \frac{13}{240}$

To find Chandra's rate $C$: $C = (A + B + C) - (A + B) = \frac{13}{240} - \frac{1}{20} = \frac{13 - 12}{240} = \frac{1}{240}$

Therefore, Chandra alone will take $240$ minutes.