Help this is soooooo hard for me
1 answer:
Answer: Choice C
Mean = 37.1
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Explanation:
Refer to the table below. The colum labeled "M" is the midpoint for each age interval. To find the midpoint, add up the endpoints and divide by 2. For example, the midpoint of 18 and 24 is (18+24)/2 = 42/2 = 21. Notice how the values of M are increasing by 7 each time.
The column labeled fM refers to multiplying the frequency f with the midpoint M. Example: fM = 6*21 = 126 in the first row.
Add up everything in the column labeled fM and you should get 1484. Divide this over the sum of the frequencies (40) and the mean is 1484/40 = 37.1
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Answer:
c) Is not a property (hence (d) is not either)
Step-by-step explanation:
Remember that the chi square distribution with k degrees of freedom has this formula
Where N₁ , N₂m .... are independent random variables with standard normal distribution. Since it is a sum of squares, then the chi square distribution cant take negative values, thus (c) is not true as property. Therefore, (d) cant be true either.
Since the chi square is a sum of squares of a symmetrical random variable, it is skewed to the right (values with big absolute value, either positive or negative, will represent a big weight for the graph that is not compensated with values near 0). This shows that (a) is true
The more degrees of freedom the chi square has, the less skewed to the right it is, up to the point of being almost symmetrical for high values of k. In fact, the Central Limit Theorem states that a chi sqare with n degrees of freedom, with n big, will have a distribution approximate to a Normal distribution, therefore, it is not very skewed for high values of n. As a conclusion, the shape of the distribution changes when the degrees of freedom increase, because the distribution is more symmetrical the higher the degrees of freedom are. Thus, (b) is true.