Tim thinks of a number.
2 answers:
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When h=0, that is when it hits the ground
0=70-4t-16t²
based on your previous questions, you should have learned how to complete the square
solve by copmleting the square
minus 70 both sides
-70=-4t-16t²
times both sides by -1
70=4t+16t²
16t²+4t=70
divide both sides by 16
t²+1/4t=35/8
take 1/2 of the linear coefint and square it
half of 1/4=1/8, (1/8)²=1/64
add that to both sides
t²+1/4t+1/64=35/8+1/64
factor perfect square trionomial
square root both sides, remember to take positive and negative roots
minus 1/8
or 
the 2nd solution is not valid because that gives us a negative time, before the ball was dropped
so is the solution
t≈1.97
1.97 seconds
0=70-4t-16t²
based on your previous questions, you should have learned how to complete the square
solve by copmleting the square
minus 70 both sides
-70=-4t-16t²
times both sides by -1
70=4t+16t²
16t²+4t=70
divide both sides by 16
t²+1/4t=35/8
take 1/2 of the linear coefint and square it
half of 1/4=1/8, (1/8)²=1/64
add that to both sides
t²+1/4t+1/64=35/8+1/64
factor perfect square trionomial
square root both sides, remember to take positive and negative roots
minus 1/8
the 2nd solution is not valid because that gives us a negative time, before the ball was dropped
so
t≈1.97
1.97 seconds
Answer:
The upper bound of a 99% confidence interval for the percentage satisfied for all customers in the database is 88.70%.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
Sample of 252 customers, 208 are satisfied:
This means that
99% confidence level
So , z is the value of Z that has a pvalue of
, so
.
The upper limit of this interval is:
As a percentage:
100%*0.8870 = 88.70%
The upper bound of a 99% confidence interval for the percentage satisfied for all customers in the database is 88.70%.