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Finding the Fourth Proportional to 1,389.89, 2,085.74 and 609.91

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Solution

The fourth proportional to 1,389.89, 2,085.74 and 609.91 is: 915.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.89 : 2,085.74 = 609.91 : x
  2. Step 2: Convert to fraction form
    1,389.89/2,085.74 = 609.91/x
  3. Step 3: Cross multiply
    1,389.89x = 2,085.74 × 609.91
  4. Step 4: Simplify right side
    1,389.89x = 1,272,113.68
  5. Step 5: Solve for x
    x = 1,272,113.68/1,389.89
  6. Step 6: Final answer
    x = 915.26

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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.