Noah gathered data at his school among 7th and 8th graders to see if there was an association between grade level and handedness. This table shows his data, but the number of right -handed 8th graders is missing .

Noah found there was no evidence of an association between grade level and handedness. Which of these could be the number of right-handed graders?

1)33
2)85
3)107
4)157

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

Assuming the number cube is a die numbered 1-6,
The probability of flipping a coin and getting heads and the probability of rolling a 3 on the die are independent of each other. 

-There are two sides of a coin, heads and tails. You have two possible results from the coin - heads, or tails. You have a 1 in 2 probability of getting either.

-There are six sides of a die. There are six possible results from the die - 1, 2, 3, 4, 5, and 6. You have a 1 in 6 probability of getting any of the results.

The probability of both happening (and) can be determined by multiplying the two probabilities.

Hope this helps!
-refrac532