2.25
Step-by-step explanation:
Given the cost model:
C(l) = l3 – l2 + l + 2.5
l = Length fo package
The length of a package that cost $11.00
11 = l³ - l² + l + 2.5
From the table given :
Length of mail which cost $11 will just be slightly greater Than 2 as the cost of 2 length mail cost 8.50
Taking l as 2.20
2.2^3 - 2.2^2 + 2.2 + 2.50 = 10.508
Taking a slightly higher value :
Put l = 2.25
2.25^3 - 2.25^2 + 2.25 + 2.50 = 11.078
Ww can conclude that the length of mail would be 2.25