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Finding the Fourth Proportional to 831.42, 1,139.15 and 821.17

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Solution

The fourth proportional to 831.42, 1,139.15 and 821.17 is: 1,125.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.42 : 1,139.15 = 821.17 : x
  2. Step 2: Convert to fraction form
    831.42/1,139.15 = 821.17/x
  3. Step 3: Cross multiply
    831.42x = 1,139.15 × 821.17
  4. Step 4: Simplify right side
    831.42x = 935,435.81
  5. Step 5: Solve for x
    x = 935,435.81/831.42
  6. Step 6: Final answer
    x = 1,125.11

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.