Qualcomm interview questions

You have 2 buckets in a room and one bucket has 17 Red balls, 19 Green Balls, 21 Blue Balls, 23 Yellow Balls. You are blindfolded and you need to pick one ball at a time and put in the bucket#2. You should stop at a point where you are confident that the color of the ball you are putting in already exists in the bucket#2. When would you stop?

You have 8 balls. 7 are 150 grams and 1 is 152 grams. With minimum (2) iterations find out the heaviest ball with the weighing machine.

What is difference between source coding, channel coding and modulation?

What is fading? Types? What is small-scale and long-scale fading