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Finding the Fourth Proportional to 1,438.90, 1,985.67 and 817.90

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Solution

The fourth proportional to 1,438.90, 1,985.67 and 817.90 is: 1,128.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,438.90 : 1,985.67 = 817.90 : x
  2. Step 2: Convert to fraction form
    1,438.90/1,985.67 = 817.90/x
  3. Step 3: Cross multiply
    1,438.90x = 1,985.67 × 817.90
  4. Step 4: Simplify right side
    1,438.90x = 1,624,086.50
  5. Step 5: Solve for x
    x = 1,624,086.50/1,438.90
  6. Step 6: Final answer
    x = 1,128.70

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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.