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Finding the Fourth Proportional to 661.65, 991.74 and 431.01

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Solution

The fourth proportional to 661.65, 991.74 and 431.01 is: 646.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.65 : 991.74 = 431.01 : x
  2. Step 2: Convert to fraction form
    661.65/991.74 = 431.01/x
  3. Step 3: Cross multiply
    661.65x = 991.74 × 431.01
  4. Step 4: Simplify right side
    661.65x = 427,449.86
  5. Step 5: Solve for x
    x = 427,449.86/661.65
  6. Step 6: Final answer
    x = 646.04

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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.