# NCERT Exemplar Solutions Class 8 Mathematics Solutions for Mensuration - Exercise in Chapter 11 - Mensuration

Question 23 Mensuration - Exercise

A covered wooden box has the inner measures as 115 cm, 75 cm and 35 cm and thickness of wood as 2.5 cm. The volume of the wood is

(a) 85,000 cm^3 (b) 80,000 cm^3 (c) 82,125 cm^3 (d) 84,000 cm^3

The correct answer is option (c) 82,125 cm^3

Explanation:

The thickness of the wooden box is 2.5 cm

Then the outer measure of the wooden box be 115+5, 75+5, 35+5

Thus, the outer volume be = (120)(80)(40)

Outer volume = 384000 cm^3

Given that, the inner volume = (115)(80)(40)

Inner volume = 301875 cm^3

Hence, the volume of a wood = Outer volume – Inner volume

V = 384000 – 301875 cm^3

V= 82125 cm^3

Video transcript
"hello students my name is megha and i am a tutor at lido learning in this q a video we will explore the concept of mensuration the a covered wooden box has the inner measures as one 15 centimeters 75 centimeter and 35 centimeter and the thickness of the wood as 2.5 centimeter the volume of the wood is okay so we have given the thickness of the box is 2.5 centimeter therefore the outer measure outer measure will be equals to let's write the outer measures outer measure will be 115 plus 5 right and which is equals to 120 and 75 plus 5 why we are adding five and not two point five because thickness of wood is given for the one side and we have to multiply it with two so that it is covered two side it covers two side both the two sides this will be equal to 80 and one more side this is 35 centimeter plus five this will be equals to 40 centimeter right now outer volume outer volume will be equals to ln to be into h boxes is rectangular so 120 into 18 to 40 so outer volume will be equals to 384 triple zero centimeter cube right now inner volume how do we find inner volume inner volume is equals to 115 into 80 into 40 so this will be equal to inner volume 301 875 centimeter cube right therefore what we have to find volume of wood volume of wood will be equals to outer volume minus inner volume so this will be equals to 384 double 0 minus 301875 so this will be equals to after calculating this will be equals to 8 2 1 2 5 centimeter cube right if you have any query in this question please drop a comment below and subscribe to our channel for more updates thank you"
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