Simplify 6x+(- 9)-9(5x+5)+x
1 answer:
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Answer:
The required probability is 0.55404.
Step-by-step explanation:
Consider the provided information.
The number of typographical errors on a page of the first booklet is a Poisson random variable with mean 0.2. The number of typographical errors on a page of second booklet is a Poisson random variable with mean 0.3.
Average error for 7 pages booklet and 5 pages booklet series is:
λ = 0.2×7 + 0.3×5 = 2.9
According to Poisson distribution:
Where is average number of events.
The probability of more than 2 typographical errors in the two booklets in total is:
Substitute the respective values in the above formula.
Hence, the required probability is 0.55404.
Answer:
The reason why standard deviation of the entire class is greater than standard deviation of males and females considered separately, is that mean values for males and females are different from each other.
Step-by-step explanation:
The concept of mean is well represented by the following formula
mean = , where x1, x2, xn are the observations and N is the number of observations (population).
Standard deviation represents the distance between each observation and the mean of the population (all observations). The formula for this parameter is:
Standard deviation =√[((x1 - x)² + (x2-x)² + ....+ (xn-x)²)/N-1], where x1, x2,..., xn are the observations and x is the mean value.
In this case you have that each height registered is an observation and the number of observations represents the N value. As you can see if the mean for males is different from that of females their standard deviation will be different too. Usually males have heigths greater than that of females (1.77 vs 1.64, in USA for example), and heights inside each group will be more similar than between groups. Then, when you mix all observation there will be an increase in standard deviation, because you are mixing very different heigths