Ex 3.2, 20
The bookshop of a particular school has 10 dozen chemistry books, 8 dozen physics books, 10 dozen economics books. Their selling prices are Rs 80, Rs 60 and Rs 40 each respectively. Find the total amount the bookshop will receive from selling all the books using matrix algebra.
Number of chemistry books = 10 dozen = 10 × 12 = 120
Number of physics books = 8 dozen = 8 × 12 = 96
Number of economics books = 10 dozen = 10 × 12 = 120
Let matrix A denote the number of books per subject.
A = [ 120 96 120 ]
Let Matrix B denote the selling price of books per subject
B = [█(𝟖𝟎@𝟔𝟎@𝟒𝟎)]
Now,
Total amount the shopkeeper receives
= Number of books × Selling price
= AB
= 〖"[ 120 96 120 ]" 〗_(𝟏 × 𝟑) [■8(𝟖𝟎@𝟔𝟎@𝟒𝟎)]_(𝟑 × 𝟏)
= 〖["120 × 80 + 96 × 60 + 120 × 40" ]〗_(1 × 1)
= "120 × 80 + 96 × 60 + 120 × 40"
= 9600 + 5760 + 4800
= 20160
Hence, total amount received by shopkeeper is Rs. 20,160
Made by
Davneet Singh
Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo
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