Answer:
70 seconds
Step-by-step explanation:
Given that;
The initial velocity 
of the bullet fired = 1120 ft/s
Initial height h = 8 feet
The expression to determine how many seconds it takes the bullet to hit the ground is:
Thus;
Replacing the value of = 1120 and h = 0 (i.e. when h =0) in the above expression; we have:
= -16t² + 1120t + 8
mulitiply through by (-)
= 16t² -1120t - 8
Divide through by 8
= 2t² - 140t - 1
The above expression forms a quadratic equation.
where;
a = 2
b = -140
c = - 1
So, by using the quadratic formula 
, we have:
= 70
Thus, the time (in seconds) it took the bullet to it the ground = 70 seconds
So each dimention is 32 by 8 by 10
so the surface area=2 times(8 times 10)+(2 times (32 times 10))+(2 times (8 times 32))=2 times 80+2 times 320+2 times 256=1312
if halved
just divide each by 2
(2 times 4 times 5)+(2 times 16 times 5)+(2 times 4 times 16)=(2 times 20)+(2 times 80)+(2 times 64)=40+160+128=328
the new surface area is 328 mm^2
Answer:
32, because 8*4 is 32
Step-by-step explanation:
Answer:
Two standard deviations
Step-by-step explanation:
The Z score is obtained using the mean and standard deviation, according to the empirical. Rule, which gives percentage of values that lie within an interval estimate in a normal distribution ;
one standard deviation lie within 68% of the mean
Two standard deviations lie within 95%
Three standard deviations lie within 99.7%
Hence, for the question given, 95% fall within 2 standard deviations of the mean
