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Finding the Fourth Proportional to 978.21, 1,457.37 and 931.77

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Solution

The fourth proportional to 978.21, 1,457.37 and 931.77 is: 1,388.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.21 : 1,457.37 = 931.77 : x
  2. Step 2: Convert to fraction form
    978.21/1,457.37 = 931.77/x
  3. Step 3: Cross multiply
    978.21x = 1,457.37 × 931.77
  4. Step 4: Simplify right side
    978.21x = 1,357,933.64
  5. Step 5: Solve for x
    x = 1,357,933.64/978.21
  6. Step 6: Final answer
    x = 1,388.18

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.