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Finding the Fourth Proportional to 780.42, 1,169.64 and 390.57

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Solution

The fourth proportional to 780.42, 1,169.64 and 390.57 is: 585.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.42 : 1,169.64 = 390.57 : x
  2. Step 2: Convert to fraction form
    780.42/1,169.64 = 390.57/x
  3. Step 3: Cross multiply
    780.42x = 1,169.64 × 390.57
  4. Step 4: Simplify right side
    780.42x = 456,826.29
  5. Step 5: Solve for x
    x = 456,826.29/780.42
  6. Step 6: Final answer
    x = 585.36

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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.