B. 9.526 to the nearest tenth C. 19.826 to the nearest whole number
1 answer:
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Step-by-step explanation:
= - 4
= a* + (3- 1) d*
- 4 = a + 2d . . . . . . . . .(i)
= - 29
= a + ( 8 - 1) d
- 29 = a + 7d . . . . . . . . (ii)
subtracting equations (i) and (ii)
25 = 5d
d = -5
placing d = -5 in equation (i)
a - 10 = -4
a = 6
For an arithmetic Progtession
= a + (n - 1)d
= 6 + (n- 1)-5
= 6 - 5n + 5
*
*
Answer:
The value of height that separates the bottom 90% of data from the top 10% is 3.507.
Step-by-step explanation:
1) Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
2) Solution to the problem
Let X the random variable that represent the grades of a population, and for this case we know the distribution for X is given by:
Where and
And the best way to solve this problem is using the normal standard distribution and the z score given by:
For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.90 of the area on the left and 0.10 of the area on the right it's z=0.816. On this case P(Z<0.816)=0.90 and P(Z>0.816)=0.1
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
So the value of height that separates the bottom 90% of data from the top 10% is 3.507.
This is a combination problem. Order does not matter and the books are all different. You would write this as 21C5 or . Combinations are not fractions.
The answer is
which = 20349 different ways these books can be chosen.