A student adds three lengths: 46.2 cm, 3.745 cm and 0.0812 cm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student adds three lengths: cm, cm and cm. Then the student multiplies the length cm by the breadth cm to find an area. Give the sum and the area with the right number of significant figures, and say how many significant figures each answer has.
Need a reminder? The key ideaShow
The mean absolute error is the mean of , and it is not taken below the least count. For the absolute errors add. For the relative errors add after the powers: . The percentage error is the relative error times 100.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The sum. cm. The number with the fewest decimal places is cm, with one. So the sum is cm, with three significant figures.
Step 2. The product. . The number with the fewest significant figures is , with two. So the area is , with two significant figures.
Answer: cm and .
Watch out. The sum has three significant figures, and the product has two. The rules for a sum and a product count different things: decimal places and significant figures.
Discussion (0)
Log in to join the discussion.
Loading…