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Finding the Fourth Proportional to 1,007.40, 1,390.98 and 697.80

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Solution

The fourth proportional to 1,007.40, 1,390.98 and 697.80 is: 963.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,007.40 : 1,390.98 = 697.80 : x
  2. Step 2: Convert to fraction form
    1,007.40/1,390.98 = 697.80/x
  3. Step 3: Cross multiply
    1,007.40x = 1,390.98 × 697.80
  4. Step 4: Simplify right side
    1,007.40x = 970,625.84
  5. Step 5: Solve for x
    x = 970,625.84/1,007.40
  6. Step 6: Final answer
    x = 963.50

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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.