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Finding the Fourth Proportional to 987.21, 1,358.42 and 957.15

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Solution

The fourth proportional to 987.21, 1,358.42 and 957.15 is: 1,317.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.21 : 1,358.42 = 957.15 : x
  2. Step 2: Convert to fraction form
    987.21/1,358.42 = 957.15/x
  3. Step 3: Cross multiply
    987.21x = 1,358.42 × 957.15
  4. Step 4: Simplify right side
    987.21x = 1,300,206.92
  5. Step 5: Solve for x
    x = 1,300,206.92/987.21
  6. Step 6: Final answer
    x = 1,317.05

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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.