Of the 1,000 students in a local college, 420 own brand X mobile phones and 580 own brand Y mobile phones. Of these students, 80
1 answer:
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Correct Answer: First Option
Explanation:
There are two ways to find the actual roots:
a) Either solve the given quadratic equation to find the actual roots
b) Or substitute the value of Possible Rational Roots one by one to find out which satisfies the given equation.
Method a is more convenient and less time consuming, so I'll be solving the given equation by factorization to find its actual roots. To find the actual roots set the given equation equal to zero and solve for x as given below:
This means the actual roots of the given equation are 3 and -4. So first option gives the correct answer.
Answer:
Step-by-step explanation:
Previous concepts
The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".
The exponential distribution is "the probability distribution of the time between events in a Poisson process (a process in which events occur continuously and independently at a constant average rate). It is a particular case of the gamma distribution". The probability density function is given by:
And 0 for other case. Let X the random variable that represent "The number of years a radio functions" and we know that the distribution is given by:
Or equivalently:
Solution to the problem
For this case we are interested in the total T, and we can find the mean and deviation for this like this:
If we solve for T we got:
And the expected value is given by:
And we can find the variance like this:
And then the deviation is given by:
And the distribution for the total is:
And we want to find this probability:
And we can use the z score formula given by:
And replacing we got this: