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Finding the Fourth Proportional to 1,287.76, 1,931.64 and 422.16

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Solution

The fourth proportional to 1,287.76, 1,931.64 and 422.16 is: 633.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.76 : 1,931.64 = 422.16 : x
  2. Step 2: Convert to fraction form
    1,287.76/1,931.64 = 422.16/x
  3. Step 3: Cross multiply
    1,287.76x = 1,931.64 × 422.16
  4. Step 4: Simplify right side
    1,287.76x = 815,461.14
  5. Step 5: Solve for x
    x = 815,461.14/1,287.76
  6. Step 6: Final answer
    x = 633.24

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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.