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Finding the Fourth Proportional to 1,390.84, 1,918.76 and 831.13

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Solution

The fourth proportional to 1,390.84, 1,918.76 and 831.13 is: 1,146.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.84 : 1,918.76 = 831.13 : x
  2. Step 2: Convert to fraction form
    1,390.84/1,918.76 = 831.13/x
  3. Step 3: Cross multiply
    1,390.84x = 1,918.76 × 831.13
  4. Step 4: Simplify right side
    1,390.84x = 1,594,734.84
  5. Step 5: Solve for x
    x = 1,594,734.84/1,390.84
  6. Step 6: Final answer
    x = 1,146.60

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1.5x scale

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.