Science (English Medium) Class 11 - CBSE Question Bank Solutions

Three integers are chosen at random from the first 20 integers. The probability that their product is even is

Out of 30 consecutive integers, 2 are chosen at random. The probability that their sum is odd, is

A bag contains 5 black balls, 4 white balls and 3 red balls. If a ball is selected randomwise, the probability that it is black or red ball is

Two dice are thrown simultaneously. The probability of getting a pair of aces is

An urn contains 9 balls two of which are red, three blue and four black. Three balls are drawn at random. The probability that they are of the same colour is

Five persons entered the lift cabin on the ground floor of an 8 floor house. Suppose that each of them independently and with equal probability can leave the cabin at any floor beginning with the first, then the probability of all 5 persons leaving at different floor is

A box contains 10 good articles and 6 with defects. One item is drawn at random. The probability that it is either good or has a defect is

A box contains 6 nails and 10 nuts. Half of the nails and half of the nuts are rusted. If one item is chosen at random, the probability that it is rusted or is a nail is

One mapping is selected at random from all mappings of the set A = {1, 2, 3, ..., n} into itself. The probability that the mapping selected is one to one is

Three numbers are chosen from 1 to 20. The probability that they are not consecutive is

Find the eccentricity, coordinates of foci, length of the latus-rectum of the ellipse:
 4x² + 9y² = 1

Find the eccentricity, coordinates of foci, length of the latus-rectum of the ellipse:

 5x² + 4y² = 1

Find the eccentricity, coordinates of foci, length of the latus-rectum of the ellipse:

 4x² + 3y² = 1

Find the eccentricity, coordinates of foci, length of the latus-rectum of the ellipse:

 25x² + 16y² = 1600.

Find the eccentricity, coordinates of foci, length of the latus-rectum of the ellipse:

Find the equation of the ellipse whose foci are (4, 0) and (−4, 0), eccentricity = 1/3. 

Find the equation of the ellipse in the standard form whose minor axis is equal to the distance between foci and whose latus-rectum is 10. 

Find the equation of an ellipse whose eccentricity is 2/3, the latus-rectum is 5 and the centre is at the origin.

Find the equation of an ellipse with its foci on y-axis, eccentricity 3/4, centre at the origin and passing through (6, 4).