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Finding the Fourth Proportional to 780.18, 1,169.98 and 390.18

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Solution

The fourth proportional to 780.18, 1,169.98 and 390.18 is: 585.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.18 : 1,169.98 = 390.18 : x
  2. Step 2: Convert to fraction form
    780.18/1,169.98 = 390.18/x
  3. Step 3: Cross multiply
    780.18x = 1,169.98 × 390.18
  4. Step 4: Simplify right side
    780.18x = 456,502.80
  5. Step 5: Solve for x
    x = 456,502.80/780.18
  6. Step 6: Final answer
    x = 585.12

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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.