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Finding the Fourth Proportional to 780.10, 1,170.21 and 317.91

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Solution

The fourth proportional to 780.10, 1,170.21 and 317.91 is: 476.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.10 : 1,170.21 = 317.91 : x
  2. Step 2: Convert to fraction form
    780.10/1,170.21 = 317.91/x
  3. Step 3: Cross multiply
    780.10x = 1,170.21 × 317.91
  4. Step 4: Simplify right side
    780.10x = 372,020.46
  5. Step 5: Solve for x
    x = 372,020.46/780.10
  6. Step 6: Final answer
    x = 476.89

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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.