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Finding the Fourth Proportional to 1,222.68, 1,686.80 and 780.48

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Solution

The fourth proportional to 1,222.68, 1,686.80 and 780.48 is: 1,076.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.68 : 1,686.80 = 780.48 : x
  2. Step 2: Convert to fraction form
    1,222.68/1,686.80 = 780.48/x
  3. Step 3: Cross multiply
    1,222.68x = 1,686.80 × 780.48
  4. Step 4: Simplify right side
    1,222.68x = 1,316,513.66
  5. Step 5: Solve for x
    x = 1,316,513.66/1,222.68
  6. Step 6: Final answer
    x = 1,076.74

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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.