If three coins are tossed simultaneously, the probability of getting at least one head is

A coin is tossed $$4$$ times. What is the probability of getting heads exactly $$3$$ times?

Using given data points tabulated below, a straight line passing through the origin is fitted using least squares method. The slope of the line is

A lot had $$10$$% defective items. Ten items are chosen randomly from this lot. The probability that exactly $$2$$ of the chosen items are defective is