S.chand Class 8 Maths Solution Chapter 22 Playiing With Numbers Exercise 22 A

  Exercise 22 A

Question 1

1. The sum of the digits of a two-digit number is 9 . The number is 6 times the units digit. Find the number.

2. The sum of the digits of a two-digit number is 7 . If the digits are reversed, the new number increased by 3 equals 4 times the original number. Find the original number.

3. The sum of a number of two digits and of the number formed by reversing the digits is 110 , and the difference of the digits is 6 . Find the number.

4. A certain number between 10 and 100 is 8 times the sum of its digits, and if 45 be subtracted from it the digits will be reversed. Find the number.

5. A number consists of three digits, the right hand being zero. If the left hand and the middle digits be interchanged the number is diminished by 180 . If the left-hand digit be halved and the middle and right-hand digits be interchanged the number is diminished by 454 . Find the number.

[Hint. Let the original number be $100 a+10 b+0$, i.e., $100 a+10 b$, then, by the first condition $(100 a+10 b)-(100 b+10 a)=180 \Rightarrow a-b=2$

By the second condition, new number $=100 \times \frac{a}{2}+0+b=50 a+b$

and so $(100 a+10 b)-(50 a+b)=454 \Rightarrow 50 a+9 b=454]$.

S.chand Class 8 Maths Solution Chapter 21 Graphs Exercise 21 C

 Exercise 21 C

Question 1

1. Match each graph with the correct description :

<fig>

(a) The car was travelling at a constant speed and then stopped.

(b) The car moved at a constant speed throughout the journey.

(c) The car was travelling at a certain speed, and then increased that speed.

(d) The car was stationary at first and then moved off at a constant speed.

2. The graph shows an aeroplane's flight.

(i) What does 1 small square represent :

(a) horizontally

(b) vertically?

(ii) For how long was the aeroplane climbing?

(iii) What was the aeroplane's speed whilst climbing ?

(iv) How long was the plane in level flight?

(v) How long did the whole flight take?

3. Akshat was travelling in his car to a meeting. He set off from home at 6 a.m. and stopped on the way for a break. This distance-time graph shows his journey. Read the graph and answer the questions given below :

(i) At what time did he

(a) stop for his break ?

(b) set off after his break?

(c) get to his meeting place ?

(ii) At what average speed was he travelling

(a) over the first hour?

(b) over the second hour?

(c) for the last part of his journey ?

S.chand Class 8 Maths Solution Chapter 21 Graphs Exercise 21 B

 Exercise 21 B

Question 1

1. Form a table of values showing the coordinates of the points highlighted on each of the graphs given below and hence write the equation showing the relationship between $x$ and $y$.

<fig>

2. Copy and complete the table of values for each equation. Hence draw the respective graphs.

(a) y=x+5

x	0	4	7
y

(b) y=2x

x	1	3	6
y

(c) y=2x-3

x	0	3	4	5
y

(d) y=x-5

x	5	8	9	11
y

3. 

(a) Draw the graph of the function y=5x.

(b) Read from the graph, the value of y when

(i) x=5

(ii) x=6

4. Draw a graph to convert miles to kilometres, given 1 mile $=1.6 \mathrm{~km}$. Use the graph to find :

(i) How many kilometres are approximately equal to $4.5$ miles ?

(ii) How many miles are approximately equal to $8 \mathrm{~km}$ ?

5. The following diagram shows the temperatures during a day:

<fig>

(i) Plot the points on a graph and then join the points with straight lines.

(ii) Approximately when did the temperature first reach $30^{\circ} \mathrm{C}$ ? Was the temperature increasing or decreasing at this time ?

(iii) For how long was the temperature above $40^{\circ} \mathrm{C}$ ?

(iv) By how much did the temperature fall between 4 p.m. and 6 p.m. ?

S.chand Class 8 Maths Solution Chapter 21 Graphs Exercise 21 A

 Exercise 21 A

Question 1

1. Plot the following points using the same pair of axes and the same scale for each one.

(i) $(0,18)$

(ii) $(5,8)$

(iii) $(7,0)$

(iv) $(5,-8)$

(v) $(8,-14)$

(vi) $(-15,4)$

(vii) $(-9,5)$

(viii) $(-8,-15)$

(ix) $(-12,-7)$

(x) $(-8,0)$

2. Given the following ordered pairs of numbers, write the number of the quadrant in which you find the point represented by each of these ordered pairs.

<table to be added>

Ordered Pair   Quadramt

(a) $(2,4)$

(b) $(3,-5)$

(c) $(-1,6)$

(d) $(-4,-4)$

(e) $(7,-2)$

(f) $(-5,-3)$

(g) $(6,1)$

(h) $(-3,5)$

3. Look at the map of the Zoo. What can be found at :

(a) $(8,2)$

(b) $(5,0)$

(c) $(8,9)$

(d) $(4,5)$

(e) $(4,2)$

(f) $(1,2) ?$

4. What are the coordinates of :

(a) the exit

(b) the camels

(c) the elephants

(d) the monkeys

(e) the penguins ?

5. In which quadrant does the point lie if

(a) both numbers of the ordered pair are positive?

(b) both numbers of the ordered pair are negative ?

(c) the $x$-coordinate of an ordered pair is negative and the $y$-coordinate is positive ?

(d) the $x$-coordinate of an ordered pair is positive and the $y$-coordinate is negative?

6. The radar screen shows aircraft positions. Write down the coordinates of the aircraft in various positions $A, B, C, D, E, F$ and $G$.

7. In which quadrant or on which axis will (x, y) be graphed if :

(a) $x>0$ and $y>0$ ?

(b) $x<0$ and $y<0$ ?

(c) $x>0$ and $y<0$ ?

(d) $x<0$ and $y>0$ ?