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Finding the Fourth Proportional to 1,389.75, 2,085.23 and 870.94

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Solution

The fourth proportional to 1,389.75, 2,085.23 and 870.94 is: 1,306.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.75 : 2,085.23 = 870.94 : x
  2. Step 2: Convert to fraction form
    1,389.75/2,085.23 = 870.94/x
  3. Step 3: Cross multiply
    1,389.75x = 2,085.23 × 870.94
  4. Step 4: Simplify right side
    1,389.75x = 1,816,110.22
  5. Step 5: Solve for x
    x = 1,816,110.22/1,389.75
  6. Step 6: Final answer
    x = 1,306.79

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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.