Consider 3 trials, each having the same probability of successes. Let X denote the total number of successes in these trials.
1 answer:
Since each trial has the same probability of success,
Let, <span><span><span>Xi</span>=1</span></span> if the <span><span>i<span>th</span></span></span> trial is a success (<span>0</span> otherwise). Then, <span><span>X=<span>∑3<span>i=1</span></span><span>Xi</span></span><span>X=<span>∑<span>i=1</span>3</span><span>Xi</span></span></span>,
and <span><span>E[X]=E[<span>∑3<span>i=1</span></span><span>Xi</span>]=<span>∑3<span>i=1</span></span>E[<span>Xi</span>]=<span>∑3<span>i=1</span></span>p=3p=1.8</span><span>E[X]=E[<span>∑<span>i=1</span>3</span><span>Xi</span>]=<span>∑<span>i=1</span>3</span>E[<span>Xi</span>]=<span>∑<span>i=1</span>3</span>p=3p=1.8</span></span>
So, <span><span>p=0.6</span><span>p=0.6</span></span>, and <span><span>P{X=3}=<span>0.63</span></span><span>P{X=3}=<span>0.63</span></span></span>
I thought what I did was sound, but the textbook says the answer to (a) is <span>0.60.6</span> and (b) is <span>00</span>.
Their reasoning (for (a)) is as follows:
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Answer:
The time taken for the flare to hit the ground is approximately 10.7 seconds.
Step-by-step explanation:
Given : Suppose a flare is shot from the top of a 120 foot building at a speed of 160 feet per second. The equation models the h height at t seconds of the flare.
To find : How long will it take for the flare to hit the ground?
Solution :
The equation models the h height at t seconds of the flare.
The flare to hit the ground when h=0.
Substitute in the equation,
Applying quadratic formula,
Where, a=-16, b=160 and c=120
Reject the negative value.
Therefore, the time taken for the flare to hit the ground is approximately 10.7 seconds.
Given the equation :
So, to find d , divide both sides by ( -6 )
So,
Note: when we divide two negative numbers, the result will be a positive number