Answer: The answer is (d) Accurately predicting who will be promoted at work.
Step-by-step explanation: We are given four options and asked in which of these four, we can use binomial distribution.
Binomial distribution is used in that experiments where there are only two outcomes, either success or failure.
In the given four options, (a), (c) and (d) are incorrect, because the number of outcomes are not fixed there and hence we cannot use binomial distribution.
Only option (b) will serve our purpose, as we are accurately predicting who is getting promoted at work.
Thus, the correct option is (b).
Answer:
85.7
Step-by-step explanation:
Given that two sections of a class took the same quiz. Section A had 15 students who had a mean score of 80, and Section B had 20 students who had a mean score of 90.
Section A total score = 15*80=1200
Section B total score 20*90 = 1800
Overall total score=3000
Overall total students = 15+20 =35
Hence overall mean = 
rounding off to one decimal place
overall mean = 85.7
Memorize the definition of standard deviation: the sd is the square root of the average of the squared deviations of the mean. Wow. Let's do it.
Step 1. First we need the mean. That's easy. Add them up and divide by the count. Check if you get 16.88/5 = 2.81333.
Step 2. Now we're going to subtract this from each of the values, and square the result. Don't worry about negative signs, the squaring will get rid of those. Example for the first number:
(1 - 2.813)^2 = 3.29
The list of numbers I get is (rounded, in reality round as little as possible):
3.29, 2.60, 1.41, 2.35, 1.66, 6.18
Step 3: Add them all up. I get 17.49.
Step 4: Divide by the count of numbers. 17.49/6 = 2.91
Step 5: Take the square root from this result. SQRT(2.91) = 1.707305
TIP: Use excel to do all these steps, then run the set of numbers through Excel's built-in sd function (called STDEV.P) and see that you get the same result!
