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Finding the Fourth Proportional to 1,389.70, 1,918.02 and 830.60

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Solution

The fourth proportional to 1,389.70, 1,918.02 and 830.60 is: 1,146.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.70 : 1,918.02 = 830.60 : x
  2. Step 2: Convert to fraction form
    1,389.70/1,918.02 = 830.60/x
  3. Step 3: Cross multiply
    1,389.70x = 1,918.02 × 830.60
  4. Step 4: Simplify right side
    1,389.70x = 1,593,107.41
  5. Step 5: Solve for x
    x = 1,593,107.41/1,389.70
  6. Step 6: Final answer
    x = 1,146.37

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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.