Pipe A alone can fill a tank in 8 hours. Pipe B alone can fill it in 6 hours. If both the pipes are opened and after 2 hours Pipe A is closed, then the other pipe will fill the tank in –
A farmer divides his herd of ncows among his four sons, so that the first son gets onehalf the herd, the second one-fourth, the third son $1\over5$ and the fourth son 7 cows. Then the value of nis –