Flashcards in Word Problems And Stats Deck (11)
...use the words AND or BOTH
...happen IN A ROW
...happen AT THE SAME TIME
...use the word OR
...use the phrase AT LEAST
Ask at the start of every OR question
Can both events occur?
If the answer is YES - the events can happen at the same time.
...This means the events are INDEPENDENT.
(1) add the probabilities that either happens
(2) subtract the probability that BOTH event occur
Determine the probability of the opposite of what you're looking for, and subtract it from 1 to get what you're looking for
"At Least Once" shortcut
Odds of an Event + Odds of its Complement = 1
At least once = 1-Never
Rate X Quantity (e.g. Time) = Work (or Distance)
Proportion rate problem
LABEL each item within the proportion. Then cross-multiply to solve the equation.
But be careful of inverse relationships. In these cases, set the products of the quantities equal to each other and solve.
1 kilometre = how many meters?
1 meter = how many centimetres?