Home / 312.82-427.86-307.78

Finding the Fourth Proportional to 312.82, 427.86 and 307.78

Calculator

Solution

The fourth proportional to 312.82, 427.86 and 307.78 is: 420.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.82 : 427.86 = 307.78 : x
  2. Step 2: Convert to fraction form
    312.82/427.86 = 307.78/x
  3. Step 3: Cross multiply
    312.82x = 427.86 × 307.78
  4. Step 4: Simplify right side
    312.82x = 131,686.75
  5. Step 5: Solve for x
    x = 131,686.75/312.82
  6. Step 6: Final answer
    x = 420.97

Related Problems

Find fourth proportional to 156.41, 213.93 and 153.89
Half scale
Find fourth proportional to 625.64, 855.72 and 615.56
Double scale
Find fourth proportional to 313.82, 429.23 and 308.78
Similar ratio
Find fourth proportional to 469.23, 641.79 and 461.67
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.