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Finding the Fourth Proportional to 1,391.40, 2,085.54 and 697.20

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Solution

The fourth proportional to 1,391.40, 2,085.54 and 697.20 is: 1,045.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.40 : 2,085.54 = 697.20 : x
  2. Step 2: Convert to fraction form
    1,391.40/2,085.54 = 697.20/x
  3. Step 3: Cross multiply
    1,391.40x = 2,085.54 × 697.20
  4. Step 4: Simplify right side
    1,391.40x = 1,454,038.49
  5. Step 5: Solve for x
    x = 1,454,038.49/1,391.40
  6. Step 6: Final answer
    x = 1,045.02

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.