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Finding the Fourth Proportional to 920.95, 1,270.20 and 781.45

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Solution

The fourth proportional to 920.95, 1,270.20 and 781.45 is: 1,077.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.95 : 1,270.20 = 781.45 : x
  2. Step 2: Convert to fraction form
    920.95/1,270.20 = 781.45/x
  3. Step 3: Cross multiply
    920.95x = 1,270.20 × 781.45
  4. Step 4: Simplify right side
    920.95x = 992,597.79
  5. Step 5: Solve for x
    x = 992,597.79/920.95
  6. Step 6: Final answer
    x = 1,077.80

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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.