What Is a Rational Number? - mrscote

8. Which of the following expressions have
3 7
the same sum as ? Use a number line
4 8
to show how you know.
3
7 3
a) a 7 b)
4 8 b
8 4
7
7 3
c) a 3 d)
8 4 b
8 4
Apply
9. Use integers to estimate each sum.
Then, determine each sum.
a) 5.6 3.2
b) 7.95 (4.51)
c) 0.325 (32.5)
d) 123.5 27.45
e) 82.001 100.28
f) 17.84 (0.098)
10. Is it possible to add 2 rational numbers and
get a sum that is less than both the numbers
you added? Explain your reasoning.
11. Determine each sum.
2 1
4
a) b) a 1 3 2
5 3 b
11
13 9
c) a 6 d)
4 5 b
5 2
1
9
e) 2 a1 3 f) a 17 3 4 b 5 6 b
3 5
5
g) 3 4 h) 1 a5 2 4 8
6 3 b
1
3
i) 3 a2 1 j) 2 a1 7 4 6 b
5 8 b
13. Zoe owes her mother $36.25, then Zoe
borrows another $25.35.
a) Write each amount as a rational number.
b) Use the numbers in part a.
i) Write an expression for the amount
Zoe owes.
ii) How much does Zoe owe?
c) Zoe pays back $14.75.
i) Write an expression for the amount
Zoe now owes.
ii) How much does Zoe now owe?
14. Estimate whether each sum is greater than
or less than 0. Explain how you know.
Calculate to check your prediction.
a) 0.61 0.23 b) 12.94 (12.56)
7
7
c) a 17 d) a 6 3 5 b
4 5 b
15. On Tuesday, December 23rd, the lowest
temperature in Winnipeg was 13.4°C.
By noon the next day, the temperature
had increased by 5.7°C.
a) What was the temperature at noon?
b) On Wednesday, December 24th, the lowest
temperature was 3.7°C less than the
lowest the previous day. What was the
lowest temperature on Wednesday?
c) Sketch a thermometer to show these
changes in temperature.
12. Assessment Focus What can you say about
the sign of the sum of 2 rational numbers in
each case? Include examples and explain
your reasoning.
a) Both rational numbers are positive.
b) Both rational numbers are negative.
c) One rational number is positive and
one rational number is negative.
112 UNIT 3: Rational Numbers