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Playlist CAHSEE Math Test Prep: Mathematical Reasoning 30 videos
Mathematical Reasoning Drill 1 Problem 4. What other information is needed?
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CAHSEE Math 4.4 Mathematical Reasoning 208 Views
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Description:
Mathematical Reasoning Drill 4 Problem 4. How many students were either not there to vote, or did not show a preference?
Transcript
- 00:03
Here’s a shmoopy question for you…
- 00:06
The teacher of a math class with 50 students
- 00:08
allowed the students to decide, by majority vote, what day to hold the final exam.
- 00:13
Although, with 50 rowdy students, “allowed” may not be the right word.
- 00:17
“Coerced” might be closer. The results are given in the following graph.
Full Transcript
- 00:21
How many students were either not there to vote, or did not show a preference?
- 00:26
And here are the potential answers…
- 00:32
Let’s figure out what we know.
- 00:33
There were 50 students total who were asked the question,
- 00:37
and everyone who responded is shown on the graph.
- 00:39
So if we figure out how many students are accounted for by the graph…
- 00:43
…we can subtract that number from fifty to find the number of students who didn’t vote.
- 00:48
Let’s start by figuring out the scale on the graph.
- 00:50
Every two lines we see a number that goes up by four.
- 00:54
Since the unmarked lines split the marked lines in half, we can cut four in half to
- 00:58
figure out that each horizontal line represents an increase of two.
- 01:02
So, Monday, for instance, had 14 votes. But Tuesday, Wednesday, and Thursday have bars
- 01:08
that end between lines… Actually, this isn’t too bad.
- 01:11
Since each line represents an increase of two,
- 01:14
a bar that ends between lines just counts as the midpoint of the two.
- 01:19
Since Tuesday’s bar ends between 2 and 4, it has three votes.
- 01:22
Similarly, Wednesday has five votes, and Thursday has 9.
- 01:26
Friday has 16 votes.
- 01:30
We can add these votes up to get the total number of votes casted.
- 01:33
14 plus 3 plus 5 plus 9 plus 16 equals 47 votes in total.
- 01:39
We can subtract that from 50 to get 3, which is the number of people who didn’t
- 01:44
vote for a specific day.
- 01:45
The answer is (D).
- 01:46
As in, “Detention.”
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