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Finding the Fourth Proportional to 661.68, 990.90 and 401.81

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Solution

The fourth proportional to 661.68, 990.90 and 401.81 is: 601.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.68 : 990.90 = 401.81 : x
  2. Step 2: Convert to fraction form
    661.68/990.90 = 401.81/x
  3. Step 3: Cross multiply
    661.68x = 990.90 × 401.81
  4. Step 4: Simplify right side
    661.68x = 398,148.57
  5. Step 5: Solve for x
    x = 398,148.57/661.68
  6. Step 6: Final answer
    x = 601.72

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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.