Question

1)the waterpipe has the inner diameter of3 3/4cm and a wall thickness of 5/7 cm.what is the 4 outer radius of the pipe.
2)the figure of a wooden frame is given with a picture inside.if the width of the wood everywhere is 1.2 cm,find the length and width of the picture and hence the perimeter of the picture is 18.5cm

Answer 1

The waterpipe has the inner diameter of 3 3/4cm and a wall thickness of 5/7 cm. What is the outer radius of the pipe.

Solution

The inner radius of a pipe is

$$r = \frac {d}{2} = 3 \frac {3}{4} \div 2 = \frac {15}{8} \text{ cm}$$

The outer radius of the pipe is:

$$R = r + w = \frac {15}{8} + \frac {5}{7} = \frac {145}{56} = 2 \frac {33}{56} \text{ cm}$$

Answer

$$2 \frac {33}{56} \text{ cm}$$

The second task requires more input information.