Why is his finger bleeding? What is his wife’s reaction?

Boojho while waving his hand very fast in front of his eyes, observes that his fingers appear blurred. What could be the reason for it?

A man and his wife appear for an interview for two posts. The probability of the man's slection is 1/5 and that of his wife's slection is 1//7 . The probability that atleast one of them is selected , is

While learning to ride a bicycle Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after some time. (a) Why did the bleeding stop? (b) What would be the colour of the wounded area and why?