Solution :
Let, the equation on the line representing the given situation is :
y = mx + c
Here, m is the slope and c is the y-intercept .
Putting, ( 3, 2450 ) in above equation, we get :
2450 = m(3) + c
3m + c = 2450 ...1 )
Also, putting ( 7, 3050 ) in above equation, we get :
3050 = m(7) + c
7m + c = 3050 ...2)
Solving equation 1) and 2) , we get :
4m = 600
m = 150 and c = 2000
So, equation of line will be :
y = 150x + 2000
A.)
Putting, x = 11 in above equation, we get :
y = ( 150 × 11 ) + 2000
y = $3650
B)
4100 = 150x + 2000
150x = 1100
x = 7.33
Since, number of appliances sold cannot be in decimals.
So, x = 7
Hence, this is the required solution.