The sum invested to purchase 15 shares of a company of nominal value ₹ 75 available at a discount of 20% is:

1. ₹ 60

2. ₹ 90

3. ₹ 1350

4. ₹ 900

The circumcentre of a triangle is the point which is ∶

1. at equal distance from the three sides of the triangle.

2. at equal distance from the three vertices of the triangle.

3. the point of intersection of the three medians.

4. the point of intersection of the three altitudes of the triangle.

In the given diagram, PS and PT are the tangents to the circle. SQ || PT and ∠SPT = 80°. The value of ∠QST is :

1. 140°

2. 90°

3. 80°

4. 50°