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Finding the Fourth Proportional to 780.78, 1,170.33 and 415.80

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Solution

The fourth proportional to 780.78, 1,170.33 and 415.80 is: 623.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.78 : 1,170.33 = 415.80 : x
  2. Step 2: Convert to fraction form
    780.78/1,170.33 = 415.80/x
  3. Step 3: Cross multiply
    780.78x = 1,170.33 × 415.80
  4. Step 4: Simplify right side
    780.78x = 486,623.21
  5. Step 5: Solve for x
    x = 486,623.21/780.78
  6. Step 6: Final answer
    x = 623.25

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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.