Question

jeremy has a collection of rocks. he lost the labels for the rocks, but he has a chart with the select the two rocks with a total estimated mass of 5.2 grams type of rock mass (in grams) basalt 2.369 granite 3.291 obsidian 2.82 pumice 1.986

Explanation:

To solve the problem of finding two rocks with a total estimated mass of 5.2 grams, we calculate the sum of the masses of each pair of rocks:

Step 1: Basalt + Granite

The mass of Basalt is \( 2.369 \) grams and the mass of Granite is \( 3.291 \) grams.
\[
2.369 + 3.291 = 5.66
\]
This sum is greater than \( 5.2 \) grams.

Step 2: Basalt + Obsidian

The mass of Basalt is \( 2.369 \) grams and the mass of Obsidian is \( 2.82 \) grams.
\[
2.369 + 2.82 = 5.189
\]
This sum is approximately \( 5.2 \) grams (when rounded to one decimal place, \( 5.189 \approx 5.2 \)).

Step 3: Basalt + Pumice

The mass of Basalt is \( 2.369 \) grams and the mass of Pumice is \( 1.986 \) grams.
\[
2.369 + 1.986 = 4.355
\]
This sum is less than \( 5.2 \) grams.

Step 4: Granite + Obsidian

The mass of Granite is \( 3.291 \) grams and the mass of Obsidian is \( 2.82 \) grams.
\[
3.291 + 2.82 = 6.111
\]
This sum is greater than \( 5.2 \) grams.

Step 5: Granite + Pumice

The mass of Granite is \( 3.291 \) grams and the mass of Pumice is \( 1.986 \) grams.
\[
3.291 + 1.986 = 5.277
\]
This sum is greater than \( 5.2 \) grams.

Step 6: Obsidian + Pumice

The mass of Obsidian is \( 2.82 \) grams and the mass of Pumice is \( 1.986 \) grams.
\[
2.82 + 1.986 = 4.806
\]
This sum is less than \( 5.2 \) grams.

Among all the pairs, the sum of the masses of Basalt (\( 2.369 \) grams) and Obsidian (\( 2.82 \) grams) is approximately \( 5.2 \) grams.

Answer:

The two rocks are Basalt (mass: \( 2.369 \) grams) and Obsidian (mass: \( 2.82 \) grams) as their total mass is approximately \( 5.2 \) grams (\( 2.369 + 2.82 \approx 5.2 \)).