Exercise 1.4 - Chapter 1 Number Systems Term 1 7th Maths Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated By SaraNextGen

On April 24, 2024, 11:35 AM

Question $1 .$
Fill in the blanks.
(i) $(-40) \div=40$
(ii) $25 \div-=-5$
(iii) $\overline{(-62)} \div(-4)=9$
(iv) $(-62) \div(-62)=$
Solution:
(i) $-1$
(ii) $-5$
(iii) $-36$
(iv) 1

Question $2 .$
Say True or False:
(i) $(-30) \div(-6)=-6$
(ii) $(-64) \div(-64)$ is 0
Solution:
(i) False
(ii) False

Question $3 .$
Find the values of the following.
(i) $(-75) \div 5$
(ii) $(-100) \div(-20)$
(iii) $45 \div(-9)$
(iv) $(-82) \div 82$
Solution:
(i) $\frac{-75}{5}=-15$
(ii) $\frac{-100}{-20}=5$

(iii) $\frac{45}{-9}=-5$
(iv) $\frac{-82}{82}=-1$

Question $4 .$
The product of two integers is $-135$. If one number is $-15$. Find the other integer.
Solution:
Given the product of two integers $=-135$
One of them $=-15$
$\therefore-15 \times$ Another number $=-135$
Other number $=\frac{-135}{-15}=9$
$\therefore$ The other number $=9$.
 

Question $5 .$
In 8 hours duration, with uniform decrease in temperature, the temperature dropped $24^{\circ} \mathrm{C}$. How many degrees did the temperature drop each hour?
Solution:
In 8 hours the drop in temperature $=24$
In 1 hour the drop in temperature $=\frac{24}{8}=3^{\circ}$
The temperature dropped $3^{\circ} \mathrm{C}$ every hour.

Question $6 .$
An elevator descends into a mine shaft at the rate of $5 \mathrm{~m} / \mathrm{min}$. If the descent starts from $15 \mathrm{~m}$ above the ground level, how long will it take to reach $-250 \mathrm{~m}$ ?
Solution:
The elevator's position $=15 \mathrm{~m}$ above ground level $=+15 \mathrm{~m}$
It should reach $=-250 \mathrm{~m}$
The distance to be travelled $=15-(-250) \mathrm{m}=15+(+250) \mathrm{m} 265 \mathrm{~m}$
Time taken to descend $5 \mathrm{~m}=1 \mathrm{~min}$
$\therefore$ Time required to descend $265 \mathrm{~m}=\frac{24}{8}=53 \mathrm{~min}$
 

Question $7 .$
A person lost 4800 calories in 30 days. If the calory loss is uniform, calculate the loss of calory per day.
Solution:
Loss of calory in 30 days $=4800$
$\therefore$ Loss of calory in 1 day $=\frac{4800}{30}=160$ calories
$\therefore 160$ calories lost per day.

Question $8 .$
Given $168 \times 32=5376$ then fined $(-5376) \div(-32)$.
Solution:
Given $168 \times 32=5376$
$\therefore \frac{5376}{32}=168$
Also, $\frac{-5376}{-32}=168$

Question $9 .$
How many $-4$ 's are there is $(-20)$ ?
Solution:
Number of $-4$ 's in $(-20)=\frac{-20}{-4}=5$
 

Question $10 .$
$(-400)$ divided into 10 equal parts gives
Solution:
$\frac{-400}{10}=-4$

Objective Type Questions
Question $11 .$
Which of the following does not represent an integer?
(i) $0 \div(-7)$
(ii) $20 \div(-4)$
(iii) $(-9) \div 3$
(iv) $12 \div 5$
Solution:
(iv) $12 \div 5$

Question $12 .$
$(-16) \div 4$ is the same as
(i) $-(-16 \div-4)$
(ii) $-(16) \div(-4)$
(iii) $16 \div(-4)$
(iv) $-4 \div-16$
Solution:
(iii) $16 \div(-4)$

Question $13 .$
$(-200) \div 10$ is
(i) 20
(ii) $-20$
(iii) $-190$
(iv) 210
Solution:
(ii) 20

Question $14 .$
The set of integers is not closed under
(i) Addition
(ii) Subtraction
(iii) Multiplication
(iv) Division
Solution:
(iv) Division