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Finding the Fourth Proportional to 1,020.78, 1,407.78 and 666.56

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Solution

The fourth proportional to 1,020.78, 1,407.78 and 666.56 is: 919.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,020.78 : 1,407.78 = 666.56 : x
  2. Step 2: Convert to fraction form
    1,020.78/1,407.78 = 666.56/x
  3. Step 3: Cross multiply
    1,020.78x = 1,407.78 × 666.56
  4. Step 4: Simplify right side
    1,020.78x = 938,373.36
  5. Step 5: Solve for x
    x = 938,373.36/1,020.78
  6. Step 6: Final answer
    x = 919.27

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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.