(b) if the length, width, and height are increasing at a rate of 0.1 ft/sec, 0.2 ft/sec, and 0.5 ft/sec respectively, find the rate at which the surface area of the box is changing when x = 20 ft, y = 15 ft, and z = 25 ft.

2380 units²

Step-by-step explanation:

Thinking process:

let the length be z = 25 ft

let the breadth be  x = 20 ft

let the height be y = 15 ft

surface area  = 2 (lb) + 2 (lh) + 2 (bh)

                      = 2 (25 ×20) + 2 (25 × 15) + 2 (20*15)

                      = 1000+ 750 + 600

                      = 2350 units²

By increasing the rates by 0.1 ft/sec, 0.2 ft/sec, and 0.5 ft/sec respectively, gives 2380 units²

answer: about 22.67

step-by-step explanation: