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Finding the Fourth Proportional to 931.68, 1,395.66 and 639.12

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Solution

The fourth proportional to 931.68, 1,395.66 and 639.12 is: 957.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.68 : 1,395.66 = 639.12 : x
  2. Step 2: Convert to fraction form
    931.68/1,395.66 = 639.12/x
  3. Step 3: Cross multiply
    931.68x = 1,395.66 × 639.12
  4. Step 4: Simplify right side
    931.68x = 891,994.22
  5. Step 5: Solve for x
    x = 891,994.22/931.68
  6. Step 6: Final answer
    x = 957.40

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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.