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Finding the Fourth Proportional to 711.78, 1,065.78 and 386.16

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Solution

The fourth proportional to 711.78, 1,065.78 and 386.16 is: 578.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    711.78 : 1,065.78 = 386.16 : x
  2. Step 2: Convert to fraction form
    711.78/1,065.78 = 386.16/x
  3. Step 3: Cross multiply
    711.78x = 1,065.78 × 386.16
  4. Step 4: Simplify right side
    711.78x = 411,561.60
  5. Step 5: Solve for x
    x = 411,561.60/711.78
  6. Step 6: Final answer
    x = 578.21

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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.