A cricket coaching camp runs from the morning time on clock A to the afternoon time on clock B. How many times do the clock's hands form a right angle during the camp?

A shows 10:10 a.m. and B shows 3:20 p.m. Right angles occur every $32\frac{8}{11}$ min, at $16\frac{4}{11}+32\frac{8}{11}k$ min past midnight. Those after 10:10 run from about 10:38 to about 3:00 p.m.: 10:38, 11:10, 11:43, 12:16, 12:49, 1:22, 1:55, 2:27, 3:00, i.e. 9. (10 counts two per hour for about 5 hours.)