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Finding the Fourth Proportional to 1,247.12, 1,720.96 and 715.90

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Solution

The fourth proportional to 1,247.12, 1,720.96 and 715.90 is: 987.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.12 : 1,720.96 = 715.90 : x
  2. Step 2: Convert to fraction form
    1,247.12/1,720.96 = 715.90/x
  3. Step 3: Cross multiply
    1,247.12x = 1,720.96 × 715.90
  4. Step 4: Simplify right side
    1,247.12x = 1,232,035.26
  5. Step 5: Solve for x
    x = 1,232,035.26/1,247.12
  6. Step 6: Final answer
    x = 987.90

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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.