An experiment was conducted in which many pieces of data were collected. Considering all of the data, the limiting number of significant figures in the experiment was 3 significant figures. One of the values needed in these calculations was the barometric pressure. It was found to be 759.5 torr. What value of the barometric pressure would the student use in doing the calculations?

The value of the barometric pressure to be used in the calculations should be rounded to match the limiting number of significant figures, which is 3 in this case.

In the given value, 759.5 torr, there are 4 significant figures. To round it to 3 significant figures, we start by looking at the fourth digit, which is 5.

If the fourth digit is 5 or greater, we round up the third digit. Since 5 is greater than 5, we need to round up the preceding digit.

Therefore, the rounded value of the barometric pressure would be 760 torr.

In this case, the student would use the value of barometric pressure as 760 torr.

To understand why, let's talk about significant figures. Significant figures refer to the number of digits in a value that carry meaning or contribute to the precision of the measurement. They are used to indicate the level of uncertainty in a measured or calculated value.

In this experiment, it was determined that the limiting number of significant figures is 3. This means that all values used in the calculations should have only 3 significant figures.

Now, let's consider the value of 759.5 torr for the barometric pressure. To determine the significant figures in this value, we start counting from the first non-zero digit from the left. In this case, the first non-zero digit is 7. So, we count all the digits from 7 onwards until we reach the desired number of significant figures, which is 3.

In 759.5, there are three digits after 7 (5, 9, and 5). Therefore, the value of 759.5 torr has 3 significant figures.

However, the value of 760 torr has only 2 significant figures. So, if we round 759.5 torr to 3 significant figures, we get 760 torr. This is because any value between 755 and 764 would round to 760.

Therefore, in doing the calculations, the student would use the value of 760 torr for the barometric pressure in order to maintain consistency with the limiting number of significant figures, which is 3.

I use the rule for 0.5 to round to the even number; i.e., I would round to 760 torr. I would round 758.5 to 758.