Consider the form x^2+bx+c. Find a pair of integers whose product is c and whose sum is b. In this case, whose product is -50 and whose sum is -5.

-10,5

Write the factored form using these integers

(x-10) (x+5)

3 0

3 years ago

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 5.9 days and a standard de

FrozenT [24]

The 70th percentile is the same as the cutoff recovery time $t$ such that every point above this time falls in the longest 30%, i.e.

$\mathbb P(X>t)=0.30$

Transform to the standard normal distribution:

$\mathbb P\left(\dfrac{X-5.9}{2.5}>\dfrac{t-5.9}{2.5}\right)=\mathbb P(Z>t^*)$

where $t^*$ is the z-score corresponding to the cutoff time $t$ , which is approximately $t^*\approx0.5244$ . Solve for $t$ :

$t^*\approx0.5244=\dfrac{t-5.9}{2.5}\implies t\approx7.21\text{ days}$

6 0

4 years ago