9 engines consume 24 metric tonnes of coal, when each is working 8 hours day. How much coal is required for 8 engines, each running 13 hours a day, if 3 engines of former type consume as much as 4 engines of latter type?
Correct Answer : D
Find the total number of ways in which a black square and a white square can be selected from a chessboard such that both the squares lie either in the same row or in the same column.
In the figure above, seven congruent rectangles are assembled together perfectly to form a bigger rectangle of perimeter 130 cm. Find the area (in sq.cm) of the bigger rectangle.
P is a point outside the circle with centre O. If a straight line drawn through P intersects the circle at points A and B such that and 900 < ∠AOB < 1200, which of the following could be the radius (in cm) of the circle?