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Finding the Fourth Proportional to 918.18, 1,378.35 and 643.50

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Solution

The fourth proportional to 918.18, 1,378.35 and 643.50 is: 966.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.18 : 1,378.35 = 643.50 : x
  2. Step 2: Convert to fraction form
    918.18/1,378.35 = 643.50/x
  3. Step 3: Cross multiply
    918.18x = 1,378.35 × 643.50
  4. Step 4: Simplify right side
    918.18x = 886,968.23
  5. Step 5: Solve for x
    x = 886,968.23/918.18
  6. Step 6: Final answer
    x = 966.01

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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.