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Finding the Fourth Proportional to 1,087.40, 1,631.10 and 831.40

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Solution

The fourth proportional to 1,087.40, 1,631.10 and 831.40 is: 1,247.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,087.40 : 1,631.10 = 831.40 : x
  2. Step 2: Convert to fraction form
    1,087.40/1,631.10 = 831.40/x
  3. Step 3: Cross multiply
    1,087.40x = 1,631.10 × 831.40
  4. Step 4: Simplify right side
    1,087.40x = 1,356,096.54
  5. Step 5: Solve for x
    x = 1,356,096.54/1,087.40
  6. Step 6: Final answer
    x = 1,247.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.