A tower standing on a horizontal plane subtends a certain angle at a point 160 m apart from the foot of the tower. On advancing 100 m towards it, the tower is found to subtend an angle twice as before. The height of the tower is
A can do a work in \( 7 \frac{1}{2} \) hours and B can do the same work in \( 10 \frac{1}{2} \) hours. If they work together for \(3 \frac{1}{2}\) hours, then what part of the work will be left out?
X, Y and Z can do a piece of work in 46 days, 92 days and 23 days, respectively, X started the work. Y joined him after 2 days. If Z joined them after 8 days from the beginning then for how many days did X work?