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Finding the Fourth Proportional to 780.71, 1,170.74 and 390.60

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Solution

The fourth proportional to 780.71, 1,170.74 and 390.60 is: 585.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.71 : 1,170.74 = 390.60 : x
  2. Step 2: Convert to fraction form
    780.71/1,170.74 = 390.60/x
  3. Step 3: Cross multiply
    780.71x = 1,170.74 × 390.60
  4. Step 4: Simplify right side
    780.71x = 457,292.02
  5. Step 5: Solve for x
    x = 457,292.02/780.71
  6. Step 6: Final answer
    x = 585.74

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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.