Example 19 - Chapter 3 Class 12 Matrices (Important Question)
Last updated at April 16, 2024 by Teachoo
Chapter 3 Class 12 Matrices
Ex 3.1, 9 (MCQ) Important
Example 18 Important
Example 19 You are here
Ex 3.2, 7 (i)
Ex 3.2, 12 Important
Ex 3.2, 16 Important
Ex 3.2, 17 Important
Ex 3.2, 20 Important
Example 22 Important
Ex 3.3, 4 Important
Ex 3.3, 10 (i) Important
Ex 3.3, 12 (MCQ)
Question 15 Important Deleted for CBSE Board 2024 Exams
Question 17 Important Deleted for CBSE Board 2024 Exams
Example 25
Question 3 Important Deleted for CBSE Board 2024 Exams
Misc 6 Important
Misc 8 Important
Misc 9 (MCQ)
Chapter 3 Class 12 Matrices
Last updated at April 16, 2024 by Teachoo
Example 19 In a legislative assembly election, a political group hired a public relations firm to promote its candidate in three ways: telephone, house calls, and letters. The cost per contact (in paise) is given in matrix A as A = [■8( 40 @100@50)] The number of contacts of each type made in two cities X and Y is given by B = [■8(1000& 500 &5000@3000&1000&10,000)] Find the total amount spent by the group in the two cities X and Y. We need to calculate total amount spent by the group in two cities x & y Total amount spent = Number of contact × Cost per contact = BA = [■8(1000&500&5000@3000&1000&10,000)]_(2 × 3) [■8(40@100@50)]_(3 × 1) = [█(𝟏𝟎𝟎𝟎(𝟒𝟎)+𝟓𝟎𝟎(𝟏𝟎𝟎)+𝟓𝟎𝟎𝟎(𝟓𝟎)@𝟑𝟎𝟎𝟎(𝟒𝟎)+𝟏𝟎𝟎𝟎(𝟏𝟎𝟎)+𝟏𝟎,𝟎𝟎𝟎(𝟓𝟎))]_(𝟐 × 𝟏) = [█(40,000+50,000+250,000@120,000+100,000+500,000)] = [█(𝟑𝟒𝟎,𝟎𝟎𝟎@𝟕𝟐𝟎,𝟎𝟎𝟎)] Hence, total amount spent = [█(340,000@720,000)] Thus, Total amount spent by the group in city X = 340,000 paise = Rs. 3,400 Total amount spent by the group in city Y = 720,000 paise = Rs. 7,200 Note: We cannot do AB AB = [■8(40@100@50)]_(3 × 1) [■8(1000&500&5000@3000&1000&10,000)]_(2 × 3) Since, orders does not match, AB is not possible