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Finding the Fourth Proportional to 661.51, 990.84 and 429.65

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Solution

The fourth proportional to 661.51, 990.84 and 429.65 is: 643.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.51 : 990.84 = 429.65 : x
  2. Step 2: Convert to fraction form
    661.51/990.84 = 429.65/x
  3. Step 3: Cross multiply
    661.51x = 990.84 × 429.65
  4. Step 4: Simplify right side
    661.51x = 425,709.45
  5. Step 5: Solve for x
    x = 425,709.45/661.51
  6. Step 6: Final answer
    x = 643.54

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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.