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Finding the Fourth Proportional to 1,128.21, 1,556.90 and 630.90

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Solution

The fourth proportional to 1,128.21, 1,556.90 and 630.90 is: 870.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.21 : 1,556.90 = 630.90 : x
  2. Step 2: Convert to fraction form
    1,128.21/1,556.90 = 630.90/x
  3. Step 3: Cross multiply
    1,128.21x = 1,556.90 × 630.90
  4. Step 4: Simplify right side
    1,128.21x = 982,250.97
  5. Step 5: Solve for x
    x = 982,250.97/1,128.21
  6. Step 6: Final answer
    x = 870.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.