Question

name: date:

1. esmi is studying the age of rocks near a mid - ocean ridge. she recorded her data in kilometers (km) and millions of years (ma). the following pairs show her data as the distance from the ridge and the age of the rocks.

100 km, 25 ma
500 km, 100 ma
1,800 km, 350 ma
draw a line on the graph to show the trend of distance from the mid - ocean ridge and age of rocks.
circle the letter of the best summary of the data.

age of rock at distance from mid - ocean ridge

summary: circle the best explanation of the data.
a. the farther away the rock is located from the ridge, the younger the rock.
b. the data show no observable pattern relating the distance of rock from the ridge and the age of the rock.
c. the closer the rock is located to the ridge, the younger the rock is.

Explanation:

Step1: Analyze the data points

We have three data points: (100 km, 25 Ma), (500 km, 100 Ma), (1800 km, 350 Ma). Let's check the relationship between distance and age. For the first two points, when distance increases from 100 km to 500 km (increase by 400 km), age increases from 25 Ma to 100 Ma (increase by 75 Ma). The ratio of distance to age for the first point is $\frac{100}{25} = 4$ km/Ma, for the second point $\frac{500}{100}=5$ km/Ma, and for the third point $\frac{1800}{350}\approx5.14$ km/Ma. So as distance from the ridge increases, age also increases.

Step2: Evaluate the options

• Option A: Says farther away means younger. But our data shows farther away (more distance) means older (higher Ma). So A is wrong.
• Option B: Says no pattern. But we see a positive correlation (distance and age both increase), so there is a pattern. B is wrong.
• Option C: Says closer to ridge means younger. Since as distance increases (farther), age increases (older), so closer (less distance) means younger. This matches our data.

Answer:

C. The closer the rock is located to the ridge, the younger the rock is.