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Finding the Fourth Proportional to 1,221.84, 1,686.15 and 690.75

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Solution

The fourth proportional to 1,221.84, 1,686.15 and 690.75 is: 953.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.84 : 1,686.15 = 690.75 : x
  2. Step 2: Convert to fraction form
    1,221.84/1,686.15 = 690.75/x
  3. Step 3: Cross multiply
    1,221.84x = 1,686.15 × 690.75
  4. Step 4: Simplify right side
    1,221.84x = 1,164,708.11
  5. Step 5: Solve for x
    x = 1,164,708.11/1,221.84
  6. Step 6: Final answer
    x = 953.24

Related Problems

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Half scale
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Double scale
Find fourth proportional to 1,222.84, 1,687.53 and 691.75
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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.