Let
x = pounds of peanuts
y = pounds of cashews
z = pounds of Brazil nuts.
The total pounds is 50, therefore
x + y + z = 50 (1)
The total cost is $6.60 per pound for 50 pounds of mixture.
The total is equal to the sum of the costs of the different nuts.
Because the cost for peanuts, cashews, and Brazil nuts are $3, $10, and $9 respectively, therefore
3x + 10y + 9z = 50*6.8
3x + 10y + 9z = 340 (2)
There are 10 fewer pounds of cashews than peanuts, therefore
x = y + 10 (3)
Substitute (3) into (1) and (2).
y + 10 + y + z = 50
2y + z = 40 (4)
3(y + 10) + 10y + 9z = 340
13y + 9z = 310 (5)
From (4),
z = 40 - 2y (6)
Substitute (6) into (5).
13y + 9(40 - 2y) = 310
-5y = -50
y = 10
z = 40 - 2y = 40 - 20 = 20
x = y + 10 = 20
Answer:
Peanuts: 20 pounds
Cashews: 10 pounds
Brazil nuts: 20 pounds
Answer:
2√10
Step-by-step explanation:
√40 = √(4*10) = √4 * √10 = 2√10
Answer:
a) p-hat (sampling distribution of sample proportions)
b) Symmetric
c) σ=0.058
d) Standard error
e) If we increase the sample size from 40 to 90 students, the standard error becomes two thirds of the previous standard error (se=0.667).
Step-by-step explanation:
a) This distribution is called the <em>sampling distribution of sample proportions</em> <em>(p-hat)</em>.
b) The shape of this distribution is expected to somewhat normal, symmetrical and centered around 16%.
This happens because the expected sample proportion is 0.16. Some samples will have a proportion over 0.16 and others below, but the most of them will be around the population mean. In other words, the sample proportions is a non-biased estimator of the population proportion.
c) The variability of this distribution, represented by the standard error, is:
d) The formal name is Standard error.
e) If we divided the variability of the distribution with sample size n=90 to the variability of the distribution with sample size n=40, we have:
If we increase the sample size from 40 to 90 students, the standard error becomes two thirds of the previous standard error (se=0.667).
8 total pens....4 are black
first pick, probability of being black is 4/8
2nd pick. without replacing, probability is 3/7
probability of a black pen picked first and then another black pen picked again is : 4/8 * 3/7 = 12/56 = 0.21
Answer:
The mean is the better method.
Step-by-step explanation:
The best way to meassure the average height is throught mean. The mean of a sample is the average of that sample's height, and it will be a good estimate for the population's average height.
The mode just finds the most frequent height. Even tough the most frequent height will influence the average height, knowing only what height is the most frequent one doesnt give you enough informtation about how the height is centrally distributed.
As for the median, it is fine to use the median of a sample to estimate the median of the population, but if you use the median to estimate the average height you may have a few issues. For example, if you include babies in your population, the babies will push the average height down a lot and they are far below te median height. This, as a result, will give you a median height of a sample way above the average height of the population, becuase median just weights every person's height the same, while average will weight extreme values more, in the sense that a small proportion of extreme values can push the average far from the median.
