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Finding the Fourth Proportional to 919.50, 1,378.20 and 399.36

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Solution

The fourth proportional to 919.50, 1,378.20 and 399.36 is: 598.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.50 : 1,378.20 = 399.36 : x
  2. Step 2: Convert to fraction form
    919.50/1,378.20 = 399.36/x
  3. Step 3: Cross multiply
    919.50x = 1,378.20 × 399.36
  4. Step 4: Simplify right side
    919.50x = 550,397.95
  5. Step 5: Solve for x
    x = 550,397.95/919.50
  6. Step 6: Final answer
    x = 598.58

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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.