To solve this problem, let's break it down step by step.

Step 1: Find the total capacity of the cylindrical jar.

The total capacity of the jar is given as 1.5 liters.

Step 2: Find how much water is in the jar when it's 7/10 full.

When the jar is 7/10 full, the amount of water in the jar is: $\text{Water in the jar} = \frac{7}{10} \times 1.5 = 1.05 \, \text{liters}.$

Step 3: Determine the amount of water when the jar is 7/10 empty.

If the jar is 7/10 empty, it means the jar is 3/10 full. Therefore, the amount of water in the jar at this point will be: $\text{Water when 7/10 empty} = \frac{3}{10} \times 1.5 = 0.45 \, \text{liters}.$

Step 4: Find the amount of water to be poured out.

To make the jar 7/10 empty from its current state (7/10 full), you need to pour out: $\text{Water to pour out} = 1.05 - 0.45 = 0.6 \, \text{liters}.$

Thus, 0.6 liters of water should be poured out so that the jar becomes 7/10 empty.

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Would you like further details or have any questions?

Here are 5 related questions:

1. How would the calculation change if the jar had a capacity of 2 liters?
2. What percentage of the jar is full when it contains 0.75 liters of water?
3. How do you convert milliliters to liters in problems like this?
4. What is the volume of water if the jar is 4/5 full?
5. How would you calculate the volume if the jar were a different shape, like a cube?

Tip: Always keep track of units (liters, milliliters, etc.) when dealing with volume problems to avoid confusion.