Answer:
(B) The correct interpretation of this interval is that 90% of the students in the population should have their scores improve by between 72.3 and 91.4 points.
Step-by-step explanation:
Confidence interval is the range the true values fall in under a given <em>confidence level</em>.
Confidence level states the probability that a random chosen sample performs the surveyed characteristic in the range of confidence interval. Thus,
90% confidence interval means that there is 90% probability that the statistic (in this case SAT score improvement) of a member of the population falls in the confidence interval.
Answer:4000
Step-by-step explanation:40 times 100 is 4000
Answer:
225 m²
Step-by-step explanation:
If W is the width of the rectangle, and L is the length, then:
60 = 2W + 2L
A = WL
Use the first equation to solve for one of the variables:
30 = W + L
L = 30 − W
Substitute into the second equation:
A = W (30 − W)
A = 30W − W²
This is a parabola, so we can find the vertex using the formula x = -b/(2a).
W = -30 / (2 × -1)
W = 15
Or, we can use calculus:
dA/dW = 30 − 2W
0 = 30 − 2W
W = 15
Solving for L:
L = 30 − W
L = 15
So the maximum area is:
A = WL
A = (15)(15)
A = 225
Answer:
1.1 R5.83
1.2 R70.01
1.3 58.34%
Step-by-step explanation:
Given that he buys a pack of 12 racing cars for R49,99 then the unit cost for a car which is the total cost divided by the number of cars in a pack
= R49,99/12
= R4.17
If each car is sold for R10 then the profit made on each car which is the difference between the cost and the selling price
= R10 - R4.17
= R5.83
The profit margin on one pack of 12 racing cars
Profit margin is the ratio of the profit to the total selling price
The total profit (profit on one pack of 12 racing cars)
= R5.83 * 12
=R70.01
Total selling price = R10 * 12
=R120
Margin = R70.01 / R120
= 58.34%
