How did he make sure that the plants were true breeding?

A man has 6 friends. In how many ways can he invite one or more of his friends to a party ?

What are the different way in which transistor can be connected?

A man has 7 friends. In how many ways can he invite one or more of them to a party ?

A man has 10 friends. In how many ways he can invite one or more of them to a party?

In an Examination, a candidate has to pass in each of the four subjects. In how many ways can he fail ?

A rectangular park is to be designed whose breadth is 3 m less than its length. Its area is to be 4 square metres more than the area of a park that has already been made in the shape of an isosceles triangle with its base as the breadth of the rectangular park and of altitude 12 m. Find its length and breadth.

A uniform magnetic field of 3000 G is established along the positive z-direction. A rectangular loop of sides 10 cm and 5 cm carries a current of 12 A. What is the torque on the loop in the different cases shown in Figure? What is the force on each case? Which case corresponds to stable equilibrium?

John wants to go abroad by ship and return by air. He has a choice of 6 different ships to go and 4 airlines to return. In how many ways can he perform his journey ?

Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?