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Chapter 3 Class 12 Matrices

Serial order wise

Last updated at Dec. 23, 2019 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 @[email protected])] The number of contacts of each type made in two cities X and Y is given by B = [■8(1000& 500 &[email protected]&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&[email protected]&1000&10,000)]_(2 × 3) [■8([email protected]@50)]_(3 × 1) = [█(1000(40)+500(100)+5000(50)@3000(40)+1000(100)+10,000(50))]_(2 × 1) = [█(40,000+50,000+250,[email protected],000+100,000+500,000)] = [█(340,[email protected],000)] Hence, total amount spent = [█(340,[email protected],000)] So the total amount spent by the group in city X = 340,000 paise = Rs. 3400 So the total amount spent by the group in city X = 720,000 paise = Rs. 7200