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Finding the Fourth Proportional to 910.78, 1,256.79 and 561.40

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Solution

The fourth proportional to 910.78, 1,256.79 and 561.40 is: 774.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    910.78 : 1,256.79 = 561.40 : x
  2. Step 2: Convert to fraction form
    910.78/1,256.79 = 561.40/x
  3. Step 3: Cross multiply
    910.78x = 1,256.79 × 561.40
  4. Step 4: Simplify right side
    910.78x = 705,561.91
  5. Step 5: Solve for x
    x = 705,561.91/910.78
  6. Step 6: Final answer
    x = 774.68

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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.