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Finding the Fourth Proportional to 715.51, 987.37 and 400.78

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Solution

The fourth proportional to 715.51, 987.37 and 400.78 is: 553.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.51 : 987.37 = 400.78 : x
  2. Step 2: Convert to fraction form
    715.51/987.37 = 400.78/x
  3. Step 3: Cross multiply
    715.51x = 987.37 × 400.78
  4. Step 4: Simplify right side
    715.51x = 395,718.15
  5. Step 5: Solve for x
    x = 395,718.15/715.51
  6. Step 6: Final answer
    x = 553.06

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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.