thx for the points :) now i can give more points for quicker answers :DD
Correct answer is: P(x<6) is 0.123 and it is usual.
Solution:-
Given that the time a person takes to decide which shoes to purchase follows normal distribution. Which has mean = 8.21 minutes and standard deviation 1.90
Then probability of individual takes less than 6 minutes is
P(X<6) = ![P(z](https://tex.z-dn.net/?f=P%28z%3C%5Cfrac%7Bx-mean%7D%7Bstandard%20deviation%7D%20%29)
= ![P(z](https://tex.z-dn.net/?f=P%28z%3C%5Cfrac%7B6-8.21%7D%7B1.90%7D%20%29%3DP%28z%3C-1.163%29)
= 0.1230
Typically we say an event with a probability less than 5% is unusual.
But here P(X<6) = 0.123 is greater than 5% hence this is usual.
There are 12 inches per foot and 3 feet per yard. To convert inches to yards divide by 12*3=36.
76/36=2 and 1/9 yards.
How to find "a"???
Pick a point on the graph other than the vertex. Let's say you see the line pass through (1,5) and the vertex is at (3,4)...
First the vertex gives you this...
y = a (x - 3)2 + 4
Put the values (1,5) into this equation.
5 = a (1 - 3)2 + 4
Solve for a
5 = a*(-2)2 + 4
5 = 4a + 4
1 = 4a
1/4 = a
Final equation is
y = 1/4*(x - 3)2 + 4