Answer:
0.333n + 28 ; 33.3 ; $41.653
Explanation:
For the best fit line :
The slope of the graph :
Drawing a right angled triangle at any point on the best fit line :
Gradient = (y2 - y1) / (x2 - x1)
Gradient = (45 - 30) / (50 - 5)
Gradient = 15 / 45
Gradient = 0.333
Intercept :
Where best fit line crosses the y - axis = 28
b = 0.333n + 28
The extra cost of each extra call made made is the slope of the graph :
$0.333 = 33.3 cents
Estimated cost of 41 calls
b = 0.333(41) + 28
b = $41.653
Kindly note that, the values used were obtained from a graph which isn't lined, therefore values taken may not be very accurate.