Answer:
f(x) = 6x² - 24x + 21
Step-by-step explanation:
The equation of a quadratic function in vertex form is
f(x) = a(x - h)² + k
where (h, k) are the coordinates of the vertex and a is a multiplier
Here (h, k ) = (2, - 3 ) , then
f(x) = a(x - 2)² - 3
To find a substitute (1, 3 ) into the equation
3 = 1(1 - 2)² - 3
3 = a(- 1)² - 3
3 = a - 3 ( add 3 to both sides )
6 = a
f(x) = 6(x - 2)² - 3 ← in vertex form
= 6(x² - 4x + 4) - 3
= 6x² - 24x + 24 - 3
f(x) = 6x² - 24x + 21 ← in standard form
x = number of hours
want to find probability (P) x >= 13
x is N(14,1) transform to N(0,1) using z = (x - mean) / standard deviation so can look up probability using standard normal probability table.
P(x >= 13) = P( z > (13 - 14)/1) = P(z > -1) = 1 - P(z < -1) = 1 - 0.1587 = 0.8413
To convert that to percentage, multiply 100, to get 84.13%
Answer:
the constant of proportionality k is given by k=y/x where y and x are two quantities that are directly proportional to each other. Once you know the constant of proportionality you can find an equation representing the directly proportional relationship between x and y, namely y=kx, with your specific k.
Step-by-step explanation:
Just combine like terms: all of the x^2 together, all of the x's together and all of the numbers:
3x2+5x2+5x-2-1
8x2+5x-3 simplified, so letter A
