Question

which is the correct measurement for the location marked by the arrow?
ruler image with markings 29.9, 30.0, 30.1, 30.2 and an arrow between 30.0 and 30.1
a) 30.046
b) 30.45
c) 30.5
d) 34.5

Explanation:

Step1: Analyze the scale

The scale shows values from 29.9 to 30.2. Between 30.0 and 30.1, the scale is divided into smaller intervals. Let's find the value of each small division. The distance between 30.0 and 30.1 is 0.1, and if we assume there are, say, 10 small divisions (since it looks like a typical decimal scale), each division is \( \frac{0.1}{10}=0.01 \). But looking at the arrow, it's between 30.0 and 30.1, closer to 30.0. Let's check the options. Option B is 30.45 which is above 30.1, C is 30.5 (way above), D is 34.5 (way off). Option A is 30.046, which is between 30.0 and 30.1 (since 30.046 is 30.0 + 0.046, and 0.046 is less than 0.1).

Step2: Eliminate incorrect options

• Option B: 30.45 is greater than 30.1, but the arrow is between 30.0 and 30.1, so B is wrong.
• Option C: 30.5 is much greater than 30.1, wrong.
• Option D: 34.5 is way off the scale (scale is up to 30.2), wrong.
• Option A: 30.046 is between 30.0 and 30.1, which matches the arrow's position.

Answer:

A) 30.046