# Lecture - 4 Chapter 3 Matrices

I attribute my success to this: I never gave or took any excuse. –Florence Nightingale

00:01:42 NCERT Solutions Exercise 3.2 Question 16

00:12:12 NCERT Solutions Exercise 3.2 Question 17

00:15:32 NCERT Solutions Exercise 3.2 Question 18

00:27:32 NCERT Solutions Exercise 3.2

Question 19 A trust fund has ₹ 30,000 that must be invested in two different types of bonds. The first bond pays 5% interest per year, and the second bond pays 7% interest per year. Using matrix multiplication, determine how to divide ₹ 30,000 among the two types of bonds. If the trust fund must obtain an annual total interest of: (a) ₹ 1800 (b) ₹ 2000

00:38:02 NCERT Solutions Exercise 3.2

Question 20 The bookshop of a particular school has 10 dozen chemistry books, 8 dozen physics books, 10 dozen economics books. Their selling prices are ₹ 80, ₹ 60 and ₹ 40 each respectively. Find the total amount the bookshop will receive from selling all the books using matrix algebra.

00:41:42 NCERT Solutions Exercise 3.2 Question 21

Assume X, Y, Z, W and P are matrices of order 2 × n, 3 × k, 2 × p, n × 3 and p × k, respectively. Choose the correct answer in Exercises 21 and 22. 21. The restriction on n, k and p so that PY + WY will be defined are:

00:44:32 NCERT Solutions Exercise 3.2

Question 22 If n = p, then the order of the matrix 7X – 5Z is:

00:47:52 Transpose of a matrix, properties of transpose

00:51:52 NCERT Solutions Exercise 3.3 Question 1

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