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Finding the Fourth Proportional to 1,256.13, 1,886.93 and 639.68

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Solution

The fourth proportional to 1,256.13, 1,886.93 and 639.68 is: 960.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,256.13 : 1,886.93 = 639.68 : x
  2. Step 2: Convert to fraction form
    1,256.13/1,886.93 = 639.68/x
  3. Step 3: Cross multiply
    1,256.13x = 1,886.93 × 639.68
  4. Step 4: Simplify right side
    1,256.13x = 1,207,018.75
  5. Step 5: Solve for x
    x = 1,207,018.75/1,256.13
  6. Step 6: Final answer
    x = 960.90

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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.