Find the common difference of the A.P.

From a point P on the ground, the angle of elevation of the top of a 10 m tall building is 30^o. A flagstaff is fixed at the top of the building and the angle of elevation of the top of the flagstaff from P is 45^o. Find the length of the flagstaff and the distance of the building from the point P? [Take √3 = 1.73]

The 24^th term of an AP is twice its 10^th term. Show that its 72^nd term is 4 times its 15^th term.

A card is drawn at random from a well shuffled pack of 52 playing cards. Find the probability that the drawn card is neither a jack nor an ace.

For what values of k, the roots of the quadratic equation (k+4)x²+(k+1)x+1 = 0 are equal?