Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Additional Questions
Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Additional Questions
Tamilnadu Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Additional Questions
Additional Questions and Answers
Exercise 1.1
Question 1.
When Malar woke up her temperature was 102°F. Two hours later it was 3° lower, what was her temperature then?
Solution:
Initially Malar’s temperature = 102°F
After two hours it lowered 3° ⇒ -3°F
Here present temperature = 102° + (-3°) = 99°F
Question 2.
An elevator is on the twentieth floor. It goes down 11 floors and then up 5 floors.
What floor is the elevator on now?
Solution:
Present location of the elevator = 20th floor
If it goes down 11 floor ⇒ (-11)
= 20 +(-11) = 9th floor
If it goes up 5 floor ⇒ 9 + 5
= 14th floor
Question 3.
16 + ___ = 16. The property expressed here is ____
Solution:
16 + 0 = 16.
0 is the additive identity on integers.
Exercise 1.2
Question 1.
Roman civilization began in 509 BC and ended in 476 AD. How long did Romans civilization last.
Solution:
From the start of common era no. of years upto 476
AD = 476
From 509 BC to start of common era years = 509
Total years Roman civilization last = 476 + 509 = 985 years.
Question 2.
A submarine was situated 450 feet below sea level. If it descends 300 feet. What is its new position?
Solution:
Position of submarine = -450 ft.
Again it descends 300 feet ⇒ -300 feet
∴ New position = —450 + (-300) = -750 ft.
∴ It was 750 feet below sea level.
Question 3.
In January the high temperature recorded was 90°F and the low temperature was -2°F. Find the difference between the high and the low temperatures?
Solution:
The high temperature recorded = 90°F
The low temperature recorded = -2°F
Difference = 90°F – (-2°F)
= 90°F + (Additive inverse of -2°F)
= 90°F + (+2°F) = 92°F
Exercise 1.3
Question 1.
Ani is scuba diving. She descends 5 feet below sea level. She descends the same distance 4 more times. What is Anis final elevation?
Solution:
Ani descends 5 feet below sea level once she descends 4 more times
∴ She descends (5 × 4) + 5 feet in total = 20 + 5 = 25 feet below sea level
Question 2.
The price of a plant reduced ₹ 6 per week for 7 weeks. By how much did the price of the plant change over the 7 weeks?
Solution:
The price of plant reduced in a week = ₹ 6
∴ The price reduced in 7 weeks = 7 × 6 = 42
Question 3.
The product of three integers is -3. Determine all of the possible values for the three factors?
Solution:
Product of three integers = -3
Possible factors are (1 × -1 × 3), (-1 × -1 × -3), (1 × 1 × -3)
Exercise 1.6
Question 1.
Simplify the following using suitable properties.
(a) (-1650) × (-2) + (-1650) × (-98)
(b) (9150 × 405) – (8150 × 405)
Solution:
(a) (-1650) × (-2) + (-1650) × (-98)
= 1650 [(-1) × (-2) + (-1) × -98] = 1650 (2 + 98) [Distributive property]
= 1650 × 100= 1,65,000
(b) (9150 × 405) – (8150 × 405)
= 405 (9150 – 8150) = 405 × 1000
= 4,05,000
Question 2.
Which is greater: (9 + 7) × 1000 or 9 + 7 × 1000?
Solution:
(9 + 7) × 1000 = 16 × 1000 = 16,000
9 + 7 × 1000 = 9 + 7000 = 7,009
16,000 > 7009
∴ (9 + 7) × 1000 > [9 + 7 × 1000]
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