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Finding the Fourth Proportional to 970.78, 1,338.81 and 639.14

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Solution

The fourth proportional to 970.78, 1,338.81 and 639.14 is: 881.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    970.78 : 1,338.81 = 639.14 : x
  2. Step 2: Convert to fraction form
    970.78/1,338.81 = 639.14/x
  3. Step 3: Cross multiply
    970.78x = 1,338.81 × 639.14
  4. Step 4: Simplify right side
    970.78x = 855,677.93
  5. Step 5: Solve for x
    x = 855,677.93/970.78
  6. Step 6: Final answer
    x = 881.43

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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.