1. ## McDonald's french fries

Okay, I have no idea how to approach this problem. It is in a section all about standard distributions. But I don't understand what this problem has to do with standard distributions! This is from Devore seventh edition, chapter 4 problem 50:

In response to concerns about nutritional contents of fast foods. McDonald's has announced that it will use a new cooking oil for its french fries that will decrease substantially trans fatty acid levels and increase the amount of more benefiacial polyunsaturated fat. The company claims that 97 out of 100 people cannot detect a difference in taste between the new and old oils. Assuming that this figure is correct (as a long-run proportion), what is the approximate probability that in a random sample of 1000 individuals who have purchased fries at McDonald's.

a) At least 40 can taste the difference between the two oils?

b) At most 5% can taste the difference between the two oils?

Do I just multiply the figures by 10? Do I have to figure out mean, variance etc for the original problem and then standardize to fit the questions?

2. Originally Posted by oldguynewstudent
Okay, I have no idea how to approach this problem. It is in a section all about standard distributions. But I don't understand what this problem has to do with standard distributions! This is from Devore seventh edition, chapter 4 problem 50:

In response to concerns about nutritional contents of fast foods. McDonald's has announced that it will use a new cooking oil for its french fries that will decrease substantially trans fatty acid levels and increase the amount of more benefiacial polyunsaturated fat. The company claims that 97 out of 100 people cannot detect a difference in taste between the new and old oils. Assuming that this figure is correct (as a long-run proportion), what is the approximate probability that in a random sample of 1000 individuals who have purchased fries at McDonald's.

a) At least 40 can taste the difference between the two oils?

b) At most 5% can taste the difference between the two oils?

Do I just multiply the figures by 10? Do I have to figure out mean, variance etc for the original problem and then standardize to fit the questions?
Let X be the random variable 'number of people who can taste a difference'.

X ~ Binomial(n = 1000, p = 0.03)

Now you're probably expected to use the normal approximation to the binomial distribution to answer a) and b).

3. Originally Posted by mr fantastic
Let X be the random variable 'number of people who can taste a difference'.

X ~ Binomial(n = 1000, p = 0.03)

Now you're probably expected to use the normal approximation to the binomial distribution to answer a) and b).
Thanks Mr. Fantastic, I wasn't sure how to stretch the Binomial into an answer!

### in response to concerns ab

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