Big Ideas Math: Modeling Real Life, Grade 7
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Big Ideas Math: Modeling Real Life, Grade 7 View details
1. Rational Numbers
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Exercise 41 Page 8

Practice makes perfect

We know that the freezing point of a liquid is the temperature at which the liquid becomes a solid. We want to find the liquid with the lowest freezing point. Let's start by looking at the given table!

Liquid Freezing Point (^(∘) C)
Butter 35
Airplane fuel - 53
Honey - 3
Mercury - 39
Candle wax 53
To find which freezing point is the lowest, let's start by plotting the values of all freezing points on the number line.
plotting point
We can see on the diagram that - 53 ^(∘)C is farther to the left than - 39^(∘)C, - 3^(∘)C, 35^(∘)C, and 53^(∘)C. This means that the airplane fuel's freezing point, - 53^(∘)C, is the lowest.

We want to know whether mercury's or butter's freezing point is closer to water's freezing point. In other words, we have to find which liquid is closer to 0^(∘) C on the number line. Let's start by recalling some facts about the absolute value of a number.

  • The absolute value of a number is its distance from 0 on the number line.
  • Since distance is always greater than or equal to 0, the absolute value of any number is greater than or equal to 0.
  • The absolute value of a non-negative number is equal to the number, while the absolute value of a negative number is equal to its opposite.
We can consider the distances between different numbers and 0 on the number line.
absolute value
To find the distance from each freezing point to 0^(∘) C, we can calculate the absolute value of mercury's freezing point and butter's freezing point. Let's do it!
Liquid Freezing Point (^(∘) C) Distance from 0^(∘) C
Butter 35 |35|= 35
Mercury - 39 |- 39|= 39
Now we can plot the distances on a number line to see the order from least to greatest.
plotting point
We can see on the diagram that | 35^(∘)C| is farther left than |- 39^(∘)C|. This means that butter's freezing point of 35^(∘)C is closer to water's freezing point of 0^(∘)C.