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Finding the Fourth Proportional to 780.19, 1,169.82 and 390.30

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Solution

The fourth proportional to 780.19, 1,169.82 and 390.30 is: 585.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.19 : 1,169.82 = 390.30 : x
  2. Step 2: Convert to fraction form
    780.19/1,169.82 = 390.30/x
  3. Step 3: Cross multiply
    780.19x = 1,169.82 × 390.30
  4. Step 4: Simplify right side
    780.19x = 456,578.79
  5. Step 5: Solve for x
    x = 456,578.79/780.19
  6. Step 6: Final answer
    x = 585.21

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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.