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Finding the Fourth Proportional to 661.07, 912.57 and 421.90

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Solution

The fourth proportional to 661.07, 912.57 and 421.90 is: 582.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.07 : 912.57 = 421.90 : x
  2. Step 2: Convert to fraction form
    661.07/912.57 = 421.90/x
  3. Step 3: Cross multiply
    661.07x = 912.57 × 421.90
  4. Step 4: Simplify right side
    661.07x = 385,013.28
  5. Step 5: Solve for x
    x = 385,013.28/661.07
  6. Step 6: Final answer
    x = 582.41

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.