Step-by-step explanation:Since we want to know how much time elapsed since the object was launched until it ht the ground. At the ground, the height is 0.

Therefore the equation h(t) = 80t – 16t2 becomes 0= 80t – 16t2

Solving the equation for t gives 80t =16t2 or 16t=80 or t=5sec

The object hits the ground 5 seconds after it is launched.

7 0

3 years ago

Potatoes: Suppose the weights of Farmer Carl's potatoes are normally distributed with a mean of 9 ounces and a standard deviatio

katrin2010 [14]

Answer: a) 79.10 % b) 7% c)19.85 %

Step-by-step explanation:

a) Z = ( × - μ ) ÷ σ Where μ mean of population σ standard deviation Z is the abscissa to give the area or probability we are looking for associated to the value 10 ounces ( × )

So: Z = ( 10 - 9 ) ÷ 1.2 ⇒ Z = 1/1.2 ⇒ Z = 0.83 it has to be below this value

From Z tables we get P [ Z ≤ 0.82 ] = 0.7910 0r 79.10 %

b) Following the same procedure: We look for

P [ Z > ( x - μ ) ÷ σ ] ⇒ Z = ( 12 -10 ) ÷ 1.2 = 2.5

From Z table we get the area under the curve from the left tail up to the point Z < 2.5 ( 2.5 not included) but we were asked for the area out of that previous so 1- 0.9930 = 0.007 is the area we are looking for

So P (b) = 0.007 or 7 %

Finally between the two points above mentioned ( 10 ≤ Z ≤ 12 ) we use the previous values (taking in consideration the limits, according to the problem statement )

Z ≤ 10 Z ⇒( 10-9 ) ÷ 1.2 Z = 0.7967

Z ≥ 12 Z ⇒ ( 12 - 9 ) ÷ 1.2 Z = 0.9952

The interval is between these two points

0.9952 - 0.7967 = 0.1985 ⇒ or 19.85 %

The attached help in the understanding of the solution

5 0

3 years ago