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Finding the Fourth Proportional to 780.50, 1,171.10 and 390.48

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Solution

The fourth proportional to 780.50, 1,171.10 and 390.48 is: 585.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.50 : 1,171.10 = 390.48 : x
  2. Step 2: Convert to fraction form
    780.50/1,171.10 = 390.48/x
  3. Step 3: Cross multiply
    780.50x = 1,171.10 × 390.48
  4. Step 4: Simplify right side
    780.50x = 457,292.10
  5. Step 5: Solve for x
    x = 457,292.10/780.50
  6. Step 6: Final answer
    x = 585.90

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Double scale
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1.5x scale

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.