Case Study
Some mementos are ordered by a school for awarding their students on the occasion of Annual Day. Each memento is designed as shown in the figure, where its base ABCD is silver plated from the front side at the rate of ₹50 per cm².

Based on the above information, answer the following questions:

1. Area of △AOB is :
   (a) 50 cm²
   (b) 52 cm²
   (c) 56 cm²
   (d) 60 cm²

2. Length of the arc CD is :
   (a) 44 cm
   (b) 22 cm
   (c) 15 cm
   (d) 11 cm

3. Area of quadrant OCDO is :
   (a) 154 cm²
   (b) 77 cm²
   (c) 38.5 cm²
   (d) 30.5 cm²

4. Area of major sector formed in the figure is :
   (a) 154 cm²
   (b) 77 cm²
   (c) 100.5 cm²
   (d) 115.5 cm²

5. Total cost of silver plating is :
   (a) ₹575
   (b) ₹500
   (c) ₹450
   (d) ₹400

Assertion (A): Total surface area of semi-circle is 18.48 cm². Its radius is 14 cm.

Reason (R): Total surface area of a semi-circle of radius r is given by 2πr².

1. A is true, R is false

2. A is false, R is true

3. Both A and R are true

4. Both A and R are false

Four circular cardboard pieces, each of radius 7 cm are placed in such a way that each piece touches two other pieces. The area of the space enclosed by the four pieces is :

1. 42 cm²

2. 40 cm²

3. 21 cm²

4. 18 cm²