It might be f but I’m getting a positive 6 instead of a negative
Answer:
1/2 ; 1/4
Step-by-step explanation:
Number of cards in a deck = 52
Number of red cards = 26
Number of spades = 13
Probability of event A :
P(A) = required outcome / Total possible outcomes
P( red card) = number of red cards / total cards in deck
P(red card) = 26 / 52 = 1/2
P(spade) = number of spades / total cards in deck
P(red card) = 13 / 52 = 1 / 4
The general way to work this out is to solve the general expression for
the remaining quantity versus half-life, using logarithms. But that's not
necessary with these numbers.
Look at the numbers:
-- 3 mg is 1/4 of 12 mg.
-- 1/4 is the product of (1/2) x (1/2).
-- So the 3 mg is what's left of 12 mg after 2 half-lives.
The 26 minutes must be two half-lives.
-- The half-life of that substance is 26/2 = <em>13 minutes</em>.
Go Maggie !
