Answer:
62.17% probability that a randomly selected exam will require more than 15 minutes to grade
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

What is the probability that a randomly selected exam will require more than 15 minutes to grade
This is 1 subtracted by the pvalue of Z when X = 15. So



has a pvalue of 0.3783.
1 - 0.3783 = 0.6217
62.17% probability that a randomly selected exam will require more than 15 minutes to grade
He wants to buy flowers for me lol
Answer:
theres no solution
Step-by-step explanation:
There are no values of x that make the equation true.
No solution
We can factor by grouping. To do so, we multiply the leading coefficient with the constant at the end. In other words, a times c (ax^2 + bx + c).
15*-4 = -60
Now we need to split the b term into two pieces that multiply to -60 and add to 4.
-6 and 10 will work.
Now group one part of b with the 15x^2 and the other part with -4.
(15x^2 + 10x) + (-6x - 4)
Now factor both terms.
5x(3x+2) - 2(3x+2)
3x+2 is one of our factors and 5x-2 is the other.
(3x+2)(5x-2)=0
Now just find the zeros.
3x+2 = 0
3x = -2
x = -2/3
And
5x-2 = 0
5x = 2
x = 2/5
So the answer is x = -2/3 and x = 2/5