A polygon is convex if, for every pair of points. P and Q belonging to the polygon, the line segment PQ lies completely inside or on the polygon.

Which one of the following is NOT a convex polygon?

Items	Cost	Profit%	Marked price
P	5400	-	5860
Q	-	25	10000

Details of prices of two items P and Q are presented in the above table. The ratio of cost of item P to cost of item Q is 3 : 4. Discount is calculated as the difference between the marked price and the selling price. The profit percentage is calculated as the ratio of the difference between selling price and cost, to the cost

(Profit% = $${{Selling\,price - Cost} \over {Cost}} \times 100$$).

The discount on item Q, as a percentage of its marked price, is ________.

The ratio of boys to girls in a class is 7 to 3. Among the options below, an acceptable value for the total number of students in the class is :