Question

Mateus’s bank issued an advertisement saying that 90%, percent of its customers are satisfied with the bank’s services. Since he himself wasn't very satisfied, he suspected the ad is false. He surveyed a random sample of 80 of the bank’s customers, and found that only 80%, percent were satisfied.
Let's test the hypothesis that the actual percentage of satisfied customers is 90%, percent versus the alternative that the actual percentage is lower than that.
The table below sums up the results of 1000 simulations, each simulating a sample of 80 customers, assuming there are 90%, percent satisfied customers.
According to the simulations, what is the probability of getting a sample with 80%, percent satisfied customers or less?

Answer 1

The table seems to show that out of 1000 simulations, only 5 produce the result where 80% of customers are satisfied. Based on this, what percentage is 5/1000?

Answer 2

0.5%

Answer 3

Yup, there you have it. Slightly worse than the rate of pulling a raw 5-star in Genshin Impact.

If we want to get really technical, the question asks for "the probability of getting a sample with 80%.... or less?" But the data only goes as low as 80% in the table. So, with the information we're given, I guess we can assume that the 1000 simulations only went as low as 80, in which case your answer would be fine.

Answer 4

Thank you!

Answer 5

No problem!

Answer 6

If I remember correctly, it's about a 0.6% chance in the game.