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Finding the Fourth Proportional to 1,398.85, 1,930.67 and 839.20

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Solution

The fourth proportional to 1,398.85, 1,930.67 and 839.20 is: 1,158.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,398.85 : 1,930.67 = 839.20 : x
  2. Step 2: Convert to fraction form
    1,398.85/1,930.67 = 839.20/x
  3. Step 3: Cross multiply
    1,398.85x = 1,930.67 × 839.20
  4. Step 4: Simplify right side
    1,398.85x = 1,620,218.26
  5. Step 5: Solve for x
    x = 1,620,218.26/1,398.85
  6. Step 6: Final answer
    x = 1,158.25

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1.5x scale

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.