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Finding the Fourth Proportional to 210, 315 and 80

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Solution

The fourth proportional to 210, 315 and 80 is: 120

Step by Step Solution

  1. Step 1: Write the proportion equation
    210 : 315 = 80 : x
  2. Step 2: Convert to fraction form
    210/315 = 80/x
  3. Step 3: Cross multiply
    210x = 315 × 80
  4. Step 4: Simplify right side
    210x = 25,200
  5. Step 5: Solve for x
    x = 25,200/210
  6. Step 6: Final answer
    x = 120

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.