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Finding the Fourth Proportional to 978.39, 1,350.81 and 715.95

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Solution

The fourth proportional to 978.39, 1,350.81 and 715.95 is: 988.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.39 : 1,350.81 = 715.95 : x
  2. Step 2: Convert to fraction form
    978.39/1,350.81 = 715.95/x
  3. Step 3: Cross multiply
    978.39x = 1,350.81 × 715.95
  4. Step 4: Simplify right side
    978.39x = 967,112.42
  5. Step 5: Solve for x
    x = 967,112.42/978.39
  6. Step 6: Final answer
    x = 988.47

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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.