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Finding the Fourth Proportional to 690.28, 939.76 and 678.76

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Solution

The fourth proportional to 690.28, 939.76 and 678.76 is: 924.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.28 : 939.76 = 678.76 : x
  2. Step 2: Convert to fraction form
    690.28/939.76 = 678.76/x
  3. Step 3: Cross multiply
    690.28x = 939.76 × 678.76
  4. Step 4: Simplify right side
    690.28x = 637,871.50
  5. Step 5: Solve for x
    x = 637,871.50/690.28
  6. Step 6: Final answer
    x = 924.08

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Why These Related Problems?

These problems maintain the same ratio (1.36) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.