Assume that adults have iq scores that are normally distributed with a mean of 100100 and a standard deviation of 15. find the t
hird quartile upper q 3q3, which is the iq score separating the top 25% from the others.
1 answer:
The bell curve attached below shows the normal distribution of the data.
We are looking the value of X such as the area to its left gives the probability of 0.75
We first need the z-score which we can obtain by reading from the z-table (as shown in the second picture below)
The z-score is = 0.7734
Then we use the following formula to work out X
z-score = (X - Mean) ÷ Standard Deviation
0.7734 = (X - 100) ÷ 15
0.7734×15 = X - 100
11.601 = X - 100
X = 11.601 + 100
X = 111.601 ≈ 112
Hence the third quartile is 112
We are looking the value of X such as the area to its left gives the probability of 0.75
We first need the z-score which we can obtain by reading from the z-table (as shown in the second picture below)
The z-score is = 0.7734
Then we use the following formula to work out X
z-score = (X - Mean) ÷ Standard Deviation
0.7734 = (X - 100) ÷ 15
0.7734×15 = X - 100
11.601 = X - 100
X = 11.601 + 100
X = 111.601 ≈ 112
Hence the third quartile is 112
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Answer:
2 000 miles
Step-by-step explanation:
In the first year, Mr James travels 8 x miles = 8 000 miles.
The second year, he traveled 1 x miles = 10 000 miles.
Comparing the distance covered in the two years,
10 000 miles - 8 000 miles = 2 000 miles
Therefore, Mr James travels 2 000 more miles in the second year than he did the first year.
Let's assume that Mr James conveys himself to his place of work all through the first year in his private car. But in the second year, there were some days in which the car was not available. So he had to go for his job by public transportation. This itch during those days, could cause an increase in the distance covered from his home to his place of work for the second year.