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Finding the Fourth Proportional to 780.80, 1,172.02 and 318.56

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Solution

The fourth proportional to 780.80, 1,172.02 and 318.56 is: 478.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.80 : 1,172.02 = 318.56 : x
  2. Step 2: Convert to fraction form
    780.80/1,172.02 = 318.56/x
  3. Step 3: Cross multiply
    780.80x = 1,172.02 × 318.56
  4. Step 4: Simplify right side
    780.80x = 373,360.82
  5. Step 5: Solve for x
    x = 373,360.82/780.80
  6. Step 6: Final answer
    x = 478.18

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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.