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Finding the Fourth Proportional to 780.50, 1,170.81 and 438.50

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Solution

The fourth proportional to 780.50, 1,170.81 and 438.50 is: 657.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.50 : 1,170.81 = 438.50 : x
  2. Step 2: Convert to fraction form
    780.50/1,170.81 = 438.50/x
  3. Step 3: Cross multiply
    780.50x = 1,170.81 × 438.50
  4. Step 4: Simplify right side
    780.50x = 513,400.19
  5. Step 5: Solve for x
    x = 513,400.19/780.50
  6. Step 6: Final answer
    x = 657.78

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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.