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Finding the Fourth Proportional to 1,388, 1,915.64 and 857.16

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Solution

The fourth proportional to 1,388, 1,915.64 and 857.16 is: 1,183.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388 : 1,915.64 = 857.16 : x
  2. Step 2: Convert to fraction form
    1,388/1,915.64 = 857.16/x
  3. Step 3: Cross multiply
    1,388x = 1,915.64 × 857.16
  4. Step 4: Simplify right side
    1,388x = 1,642,009.98
  5. Step 5: Solve for x
    x = 1,642,009.98/1,388
  6. Step 6: Final answer
    x = 1,183.00

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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.