Question

Analyse the graph of climate change of 4 different countries in a particular time. Find out which two functions have same rate of change.

• A. B and C
• B. B and D
• C. A and C
• D. A and B

Answer 1

The correct option is B B and D

$\text{The rate of change}=\frac{\text{Change in y}}{\text{Change in x}}$

Let's find out the rate of change of graph A

Time (in months)	2	8
Temperature (in °C)	60	60

$\text{Rate of change}=\frac{60-60}{8-2}$
$=0$
$\therefore$The rate of change of graph A is 0.


Let's find out the rate of change of graph B

Time (in months)	2	8
Temperature (in °C)	0	60

$\text{Rate of change}=\frac{60-0}{8-2}$
$=10$
$\therefore$The rate of change of graph B is 10.


Let's find out the rate of change of graph C

Time (in months)	0	6
Temperature (in °C)	60	0

$\text{Rate of change}=\frac{0-60}{6-0}$
$=-10$
$\therefore$The rate of change of graph C is -10.


Let's find out the rate of change of graph D

Time (in months)	0	6
Temperature (in °C)	20	80

$\text{Rate of change}=\frac{80-20}{6-0}$
$=10$
$\therefore$The rate of change of graph D is 10.

Hence, the rate of change of graph B and D is same.