Answer:
We need a sample size of at least 75.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
So it is z with a pvalue of 
, so 
Now, we find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
The standard deviation is the square root of the variance. So:
With a .95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is
We need a sample size of at least n, in which n is found when M = 5. So
We need a sample size of at least 75.
Answer:
2
Step-by-step explanation:
it's literally 6-4 = 2
So the first hour it travels from 1-6 miles, the second hour it travels at least two miles. And the question is "draw the range of miles the boat could of traveled in the second hour". Well first of all the third hour is completely useless so forget about that. Now, the first hour says it traveled from 1-6 miles, we don't know how many miles it traveled for sure but it could of traveled up to 6. So in the second hour when they say "at least two miles" the boat could of travled at least two miles more than 1-6. So 1+2+3, 2+2+4, 3+2=5, 4+2=6, 5+2=7 and 6+2=8. So the boat could of traveled from 3 to 8 miles in the second hour.
50 because 50/100=2/4 and 2/4 is blue on the circle
Answer:
(1, 8.5 ) and ( - 17, 80.5 )
Step-by-step explanation:
Given the 2 equations
y = 
x² + 4x + 4 → (1)
y = - 4x + 12 → (2)
Substitute (1) into (2), that is
x² + 4x + 4 = - 4x + 12 ( multiply through by 2 to clear the fractions )
x² + 8x + 8 = - 8x + 25 ( add 8x to both sides )
x² + 16x + 8 = 25 ( subtract 25 from both sides )
x² + 16x - 17 = 0 ← in standard form
(x + 17)(x - 1) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 17 = 0 ⇒ x = - 17
x - 1 = 0 ⇒ x = 1
Substitute these values into either of the 2 equations and evaluate for y
Substituting into (2 )
x = 1 : y = - 4(1) + 12.5 = - 4 + 12.5 = 8.5 ⇒ (1, 8.5 )
x = - 17 : y = - 4(- 17) + 12.5 = 68 + 12.5 = 80.5 ⇒ (- 17, 80.5 )
