If a young son works quickly for 2 hours and prepares 16 items in a day, and his old father works slowly for 8 hours and prepares 24 items in a day, which of the following is true?
Two valves P and B can fill a sump in 37.5 minutes and 45 minutes respectively. Both valves are opened. The sump will be filled in just 30 minutes, if valve B is turned off after
The initial ratio of sugar to flour in a dough was 2 : 7. To 9 kg of the dough John added more sugar to make the sugar to flour ratio 2 : 5. How much sugar did John later add?