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Finding the Fourth Proportional to 1,391, 2,085.12 and 659.28

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Solution

The fourth proportional to 1,391, 2,085.12 and 659.28 is: 988.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391 : 2,085.12 = 659.28 : x
  2. Step 2: Convert to fraction form
    1,391/2,085.12 = 659.28/x
  3. Step 3: Cross multiply
    1,391x = 2,085.12 × 659.28
  4. Step 4: Simplify right side
    1,391x = 1,374,677.91
  5. Step 5: Solve for x
    x = 1,374,677.91/1,391
  6. Step 6: Final answer
    x = 988.27

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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.