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Finding the Fourth Proportional to 780.40, 1,170.74 and 318.43

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Solution

The fourth proportional to 780.40, 1,170.74 and 318.43 is: 477.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.40 : 1,170.74 = 318.43 : x
  2. Step 2: Convert to fraction form
    780.40/1,170.74 = 318.43/x
  3. Step 3: Cross multiply
    780.40x = 1,170.74 × 318.43
  4. Step 4: Simplify right side
    780.40x = 372,798.74
  5. Step 5: Solve for x
    x = 372,798.74/780.40
  6. Step 6: Final answer
    x = 477.70

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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.