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Finding the Fourth Proportional to 918.81, 1,378.56 and 398.88

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Solution

The fourth proportional to 918.81, 1,378.56 and 398.88 is: 598.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.81 : 1,378.56 = 398.88 : x
  2. Step 2: Convert to fraction form
    918.81/1,378.56 = 398.88/x
  3. Step 3: Cross multiply
    918.81x = 1,378.56 × 398.88
  4. Step 4: Simplify right side
    918.81x = 549,880.01
  5. Step 5: Solve for x
    x = 549,880.01/918.81
  6. Step 6: Final answer
    x = 598.47

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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.