Students can Download Maths Chapter 1 Number System Additional Questions and Answers, Notes Pdf, Samacheer Kalvi 7th Maths Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations.
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]
Question 3.
Simiplify: 80 ÷ [240 ÷ (-24)] + 7
Solution:
We have
80 ÷ [240 ÷ (-24)] + 7
= 80 ÷ \(\left[\frac{240}{-24}\right]\) + 7
= 80 ÷ (-10) + 7 = \(-\left[\frac{80}{10}\right]\) + 7 = (-8) + 7 = -1