AP EAMCET · Maths · Probability
The probability that A wakes up before the alarm rings is 0.4 . Then, the mean and variance of the number of times A wakes up before the alarm rings, in the next 7 days respectively are:
- A \(0.4,0.6\)
- B \(2.8,0.6\)
- C \(2.8,1.68\)
- D \(7,0.6\)
Answer & Solution
Correct Answer
(C) \(2.8,1.68\)
Step-by-step Solution
Detailed explanation
We are given that \(x=7\) \(\begin{aligned} & \mathrm{p}=0.7, \mathrm{q}=1-0.4=0.6 \\ & \text { Now mean }=x \cdot \mathrm{p}=7 \times 0.4=2.8 \\ & \text { Variance }=x p q=2.8 \times 0.6=1.68\end{aligned}\)
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