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Finding the Fourth Proportional to 780.68, 1,171.40 and 318.77

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Solution

The fourth proportional to 780.68, 1,171.40 and 318.77 is: 478.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.68 : 1,171.40 = 318.77 : x
  2. Step 2: Convert to fraction form
    780.68/1,171.40 = 318.77/x
  3. Step 3: Cross multiply
    780.68x = 1,171.40 × 318.77
  4. Step 4: Simplify right side
    780.68x = 373,408.51
  5. Step 5: Solve for x
    x = 373,408.51/780.68
  6. Step 6: Final answer
    x = 478.31

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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.