Home / 305.84-420.34-287.12

Finding the Fourth Proportional to 305.84, 420.34 and 287.12

Calculator

Solution

The fourth proportional to 305.84, 420.34 and 287.12 is: 394.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.84 : 420.34 = 287.12 : x
  2. Step 2: Convert to fraction form
    305.84/420.34 = 287.12/x
  3. Step 3: Cross multiply
    305.84x = 420.34 × 287.12
  4. Step 4: Simplify right side
    305.84x = 120,688.02
  5. Step 5: Solve for x
    x = 120,688.02/305.84
  6. Step 6: Final answer
    x = 394.61

Related Problems

Find fourth proportional to 152.92, 210.17 and 143.56
Half scale
Find fourth proportional to 611.68, 840.68 and 574.24
Double scale
Find fourth proportional to 306.84, 421.71 and 288.12
Similar ratio
Find fourth proportional to 458.76, 630.51 and 430.68
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.