Time taken to fill the bathtub is 8 min
time taken to drain the bathtub is 12 min
fraction of bathtub filled in 1 hour=1/8
fraction of bathtub drained in 1 hour=1/12
fraction that will be filled in a minute given that both taps are opened at he same time:
1/8-1/12
=1/24
thus time taken for the bathtub to be filled is 24 min
There are 52 cards in a standard deck, and 4 suits. There is one 9 per suit, so 4 cards, plus one 10 per suit, so 8 cards. 8 cards divided by 52 cards in a deck is 0.15384615 or 0.154.
Monica's kitten weighs 1.15 more pounds than Maryan's kittens.
Since you mentioned the fundamental counting principle, I assume you are looking for the total number of possibilities.
If you are picking a month, there are 12 options.
If you are selecting a day of the week, there are 7 options.
If you are doing both, you multiply the two numbers together.
12 x 7 = 84