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Finding the Fourth Proportional to 780, 1,170 and 472.20

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Solution

The fourth proportional to 780, 1,170 and 472.20 is: 708.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    780 : 1,170 = 472.20 : x
  2. Step 2: Convert to fraction form
    780/1,170 = 472.20/x
  3. Step 3: Cross multiply
    780x = 1,170 × 472.20
  4. Step 4: Simplify right side
    780x = 552,474
  5. Step 5: Solve for x
    x = 552,474/780
  6. Step 6: Final answer
    x = 708.30

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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.