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Finding the Fourth Proportional to 1,290.51, 1,780.78 and 731.02

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Solution

The fourth proportional to 1,290.51, 1,780.78 and 731.02 is: 1,008.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.51 : 1,780.78 = 731.02 : x
  2. Step 2: Convert to fraction form
    1,290.51/1,780.78 = 731.02/x
  3. Step 3: Cross multiply
    1,290.51x = 1,780.78 × 731.02
  4. Step 4: Simplify right side
    1,290.51x = 1,301,785.80
  5. Step 5: Solve for x
    x = 1,301,785.80/1,290.51
  6. Step 6: Final answer
    x = 1,008.74

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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.