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Finding the Fourth Proportional to 780.89, 1,171.51 and 312.39

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Solution

The fourth proportional to 780.89, 1,171.51 and 312.39 is: 468.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.89 : 1,171.51 = 312.39 : x
  2. Step 2: Convert to fraction form
    780.89/1,171.51 = 312.39/x
  3. Step 3: Cross multiply
    780.89x = 1,171.51 × 312.39
  4. Step 4: Simplify right side
    780.89x = 365,968.99
  5. Step 5: Solve for x
    x = 365,968.99/780.89
  6. Step 6: Final answer
    x = 468.66

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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.