Elementary Statistics - Probability - General Aptitude (GA) Previous Year Questions

In any given year, the probability of an earthquake greater than Magnitude 6 occurring in the Garhwal Himalayas is 0.04. The average time between successive occurrences of such earthquakes is ____ years.

10% of the population in a town is HIV+. A new diagnostic kit for HIV detection is available. This kit correctly identifies HIV+ individuals 95% of the time, and HIV- individuals 89% of the time. A particular patient is tested using this kit and is found to be positive. The probability that the individual is actually positive is ______

A game consists of spinning an arrow around a stationary disk as shown below. When the arrow comes to rest, there are eight equally likely outcomes. It could come to rest in any one of the sectors numbered 1, 2, 3, 4, 5, 6, 7 or 8 as shown.
Two such disks are used in a game where their arrows are independently spun.
What is the probability that the sum of the numbers on the resulting sectors upon spinning the two disks is equal to 8 after the arrows come to rest?

Let \(X\) be a continuous random variable denoting the temperature measured. The range of temperature is \([0, 100]\) degree Celsius and let the probability density function of \(X\) be \(f(x) = 0.01\) for \(0 \le X \le 100\).
The mean of \(X\) is ______