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Finding the Fourth Proportional to 900.78, 1,242.90 and 551.40

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Solution

The fourth proportional to 900.78, 1,242.90 and 551.40 is: 760.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    900.78 : 1,242.90 = 551.40 : x
  2. Step 2: Convert to fraction form
    900.78/1,242.90 = 551.40/x
  3. Step 3: Cross multiply
    900.78x = 1,242.90 × 551.40
  4. Step 4: Simplify right side
    900.78x = 685,335.06
  5. Step 5: Solve for x
    x = 685,335.06/900.78
  6. Step 6: Final answer
    x = 760.82

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1.5x scale

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.