Chapter 9 Commercial Mathematics Ex 9.1 Solutions

We find the pass percentage using the unitary method ∴ The pass percentage for the examination is 85%.

Let 168 gms be x% of 8.4 kg i.e., let 168 gms be of 8400 gms ∴ 168 = × 8400 ∴ x = = 2 ∴ 168 gms is 2% of 8.4 kg.

Let x and y represent the length and breadth of the rectangle respectively. ∴ The original area of the rectangle = xy There is a 20% decrease in length. Let k % be the required increase in breadth Given that the new and old areas should be equal. ∴ 100 + k = 125 ∴ k = 125 – 100 = 25 ∴ Breadth should be increased by 25% so that the area remains same.

A person can buy 5 kg of rice for ₹ 600 after the increase in price ∴ New price of rice = = ₹ 120/kg …..(i) Let ‘x’ be the initial price per kg of rice. There is a 20% increase in the price of rice. Thus the new price of the rice will be given as ∴ The initial price of rice is ₹ 100 per kg

Let 3% be x % of 5%. Then ∴ x = = 60 ∴ 3% is 60% of 5%.

Let the price of the book be ₹ x. After the first 20% discount, the price of the book becomes After another 20% discount, the price of the book becomes This price = ₹ 64 …..[Given] ∴ x = 64 ∴ x = 4 × 25 = 100 Thus, Amount of the book after one discount = (100) = 80 …..[from (i)] ∴ The additional amount that Madhavi would have paid = 80 – 64 = ₹ 16

Let ₹ x and ₹ y be the price of a table and chair respectively. The price of the table is 40% more than the price of a chair ∴ × 100 = 40 We need to find by how much percent is the price of a chair less than that of a table. ∴ The price of a chair is 28.57% less than the price of a table.

Batsman scores 4 fours (boundaries) and 5 sixes in 92 runs. Number of runs scored by fours and sixes = 4 × 4 + 5 × 6 = 46 ∴ 92 – 46 = 46 Let 46 be x% of 92. Then 46 = × 92 ∴ x = = 50 ∴ 50% of the total runs were scored by running between the wickets.