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Finding the Fourth Proportional to 1,287.72, 1,931.68 and 637.80

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Solution

The fourth proportional to 1,287.72, 1,931.68 and 637.80 is: 956.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.72 : 1,931.68 = 637.80 : x
  2. Step 2: Convert to fraction form
    1,287.72/1,931.68 = 637.80/x
  3. Step 3: Cross multiply
    1,287.72x = 1,931.68 × 637.80
  4. Step 4: Simplify right side
    1,287.72x = 1,232,025.50
  5. Step 5: Solve for x
    x = 1,232,025.50/1,287.72
  6. Step 6: Final answer
    x = 956.75

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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.