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Finding the Fourth Proportional to 1,030.78, 1,421.78 and 638

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Solution

The fourth proportional to 1,030.78, 1,421.78 and 638 is: 880.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,030.78 : 1,421.78 = 638 : x
  2. Step 2: Convert to fraction form
    1,030.78/1,421.78 = 638/x
  3. Step 3: Cross multiply
    1,030.78x = 1,421.78 × 638
  4. Step 4: Simplify right side
    1,030.78x = 907,095.64
  5. Step 5: Solve for x
    x = 907,095.64/1,030.78
  6. Step 6: Final answer
    x = 880.01

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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.