Answer:
(i) The student who weighed the rock 20 times.
Step-by-step explanation:
The margin of error of a confidence interval is:
In which z is related to the confidence level, 
is the standard deviation of the population and n is the size of the sample.
From the equation above, the larger the size of the sample, the lower the margin is, that is, the narrower the interval is.
In this question:
A student weighed the rock 20 times and other the 5. From above, the one who weighed the rock 20 times will have the more precise interval.
So the correct answer is:
(i) The student who weighed the rock 20 times.
you divide 13 by 20, so you get 0.65. Multiply that by 100 and you get 65%!
65% of cans are recycled.
Ducks have 1 head. Dogs have 1 head.
Ducks have 2 feet. Dogs have 4 feet.
If x = no. of ducks and g = no. of dogs
x + g = 25
2x + 4g = 80
Let's use substitution to solve.
x + g = 25 ⇒ x = 25 - g
replace x with 25 - g in the other equation and solve for g
2x + 4g = 80
2(25 - g) + 4g = 80
50 - 2g + 4g = 80
50 + 2g = 80
2g = 30
g = 15
Now use g = 15 in an earlier equation to find x.
x + g = 25
x + 15 = 25
x = 10
You make 35% a decimal so it would be 0.35 then you multiply that by 125 (0.35*125) because it says "of"
Answer:
x = 7
Step-by-step explanation:
The angle adjacent to the 70 degree angle is also 70 degrees. We assume that there are four 90-degree angles in the center of the figure. Thus, 8x - 36 + 70 + 90 = 180 (the sum of the interior angles is 180 degrees).
Solving 8x - 36 + 70 + 90 = 180 for x:
8x - 36 = 20, or 8x = 56.
Dividing both sides by 8 yields x = 7.
