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Finding the Fourth Proportional to 1,256.90, 1,886.12 and 640.26

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Solution

The fourth proportional to 1,256.90, 1,886.12 and 640.26 is: 960.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,256.90 : 1,886.12 = 640.26 : x
  2. Step 2: Convert to fraction form
    1,256.90/1,886.12 = 640.26/x
  3. Step 3: Cross multiply
    1,256.90x = 1,886.12 × 640.26
  4. Step 4: Simplify right side
    1,256.90x = 1,207,603.99
  5. Step 5: Solve for x
    x = 1,207,603.99/1,256.90
  6. Step 6: Final answer
    x = 960.78

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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.