Answer:
A sample of 499 is needed.
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
.
The margin of error is given by:

In this question, we have that:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 90% confidence level with an error of at most 0.03
We need a sample of n, which is found when
. So






Rounding up
A sample of 499 is needed.
9514 1404 393
Answer:
(c) 162 cm
Step-by-step explanation:
The centroid divides a median into parts with the ratio 1:2, so RL:LD = 1:2. Then RL:RD = 1:(1+2), and RD = 3RL.
RD = 3·54 cm
RD = 162 cm
Answer:

Step-by-step explanation:
Given

Required
Simplify
Rewrite as:

Take LCM

Apply law of indices

1.70 - 0.45 = 1.25
1500 ÷ 1.25 = 1200
Gina must sell 1200 cards before she can make a profit
Answer:
18
Step-by-step explanation:
-2(3x+4)+7x=10
-6x-8+7x=10
x=10+8
x=18