Answer: 4) 157
Step-by-step explanation:
We know that there is no association between the grade level and the andedness, then we should find that the ratio between left handeds and right handed is the same for both grades.
In 7-th grade we have:
Left handed : 11
Right handed: 72
The ratio is 11/72 = 0.14
Then, the ratio for the 8-th graders must be about the same:
Left handed: 24
Right handed: X
Ratio: 24/X
Let's start with the bigger option, X = 157.
24/157 = 0.15
Ok, we now see that with the bigger option we obtained almost the same ratio (if we use the smaller values for X, we will get a ratio bigger than 0.15, so 0.15 is the better aproximation that we can find to the 0.14 of the 7-th graders)
Then the correct option is 4) 157
The answer to your question is b
Solution: We are given:

We need to find the z value corresponding to probability 0.84, in order to find the how much money almost 84% of gamblers spent at casino.
Using the standard normal table, we have:

Now we will use the z score formula to find the required amount:





approximately
Therefore, almost 84% of gamblers spent more than $720 amount of money at this casino.
The triangle has to equal to 180. So add them up and equal it to 180