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

Rewrite of the  statement in the form "p if and only if q".

 s : If a tumbler is half empty, then it is half full and if a tumbler is half full, then it is half empty.

If a, b, c, d are in G.P., prove that:

(a² + b²), (b² + c²), (c² + d²) are in G.P.

If a, b, c, d are in G.P., prove that:

(a² − b²), (b² − c²), (c² − d²) are in G.P.

If a, b, c, d are in G.P., prove that:

\[\frac{1}{a^2 + b^2}, \frac{1}{b^2 - c^2}, \frac{1}{c^2 + d^2} \text { are in G . P } .\]

If a, b, c, d are in G.P., prove that:

(a² + b² + c²), (ab + bc + cd), (b² + c² + d²) are in G.P.

Determine the contrapositive of the statement:

 If Mohan is a poet, then he is poor.

If a, b, c are in G.P., then prove that:

Determine the contrapositive of the statement:

 Only if Max studies will he pass the test.

Determine the contrapositive of the statement:

If she works, she will earn money.

Determine the contrapositive of the statement:

If it snows, then they do not drive the car.

Determine the contrapositive of the statement:

 It never rains when it is cold.

If the 4^th, 10^th and 16^th terms of a G.P. are x, y and z respectively. Prove that x, y, z are in G.P.

Determine the contrapositive of the statement:

 If Ravish skis, then it snowed.

Determine the contrapositive of the statement:

If x is less than zero, then x is not positive.

Determine the contrapositive of the statement:

 If he has courage he will win.

If pth, qth, rth and sth terms of an A.P. be in G.P., then prove that p − q, q − r, r − s are in G.P.

Determine the contrapositive of the statement:

 It is necessary to be strong in order to be a sailor.

Determine the contrapositive of the statement:

Only if he does not tire will he win.