Probability and Data — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
A tally bundle of four straight lines and one slash counts as 4.
Corrected: A tally bundle of four straight lines and one slash counts as 5.
Tally bundles are groups of five marks, with the fifth crossing the first four.
2. Fix the sentence:
If a bar reaches 6 and another reaches 9, the taller bar shows fewer items.
Corrected: If a bar reaches 6 and another reaches 9, the taller bar shows more items.
Bar height grows as the count grows, so taller means more items collected.
3. Fix the sentence:
Drawing any color marble from a bag containing only one color is impossible.
Corrected: Drawing any color marble from a bag containing only one color is certain.
When all items match the event, every draw must be successful and certain.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. An event that probably will happen but is not certain is called likely.
Likely events happen most of the time but may sometimes fail to occur.
2. Three full tally bundles equal a count of 15.
Tally bundles are groups of five, so three bundles total fifteen marks.
3. If a bar graph shows 7 cats and 4 dogs, there are 3 more cats than dogs.
Subtraction tells you the difference between two bar heights on a graph.
4. A coin landing on tails has a probability of 1 out of 2.
A coin has two equal outcomes, so each side has a one-in-two chance.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. How can you find the total count from a tally chart with bundles and extras?
Sample answer: Skip-count the bundles by fives, then add the leftover single marks to that subtotal to get the total.
Skip-counting by fives plus adding extras gives the full count quickly.
2. Why is pulling any marble from a bag with only red marbles certain?
Sample answer: Every marble in the bag is red, so any draw must be red and the event always happens.
When all items match the desired event, the event is guaranteed to occur.