Home / 920-1,380-312

Finding the Fourth Proportional to 920, 1,380 and 312

Calculator

Solution

The fourth proportional to 920, 1,380 and 312 is: 468

Step by Step Solution

  1. Step 1: Write the proportion equation
    920 : 1,380 = 312 : x
  2. Step 2: Convert to fraction form
    920/1,380 = 312/x
  3. Step 3: Cross multiply
    920x = 1,380 × 312
  4. Step 4: Simplify right side
    920x = 430,560
  5. Step 5: Solve for x
    x = 430,560/920
  6. Step 6: Final answer
    x = 468

Related Problems

Find fourth proportional to 460, 690 and 156
Half scale
Find fourth proportional to 1,840, 2,760 and 624
Double scale
Find fourth proportional to 921, 1,381.50 and 313
Similar ratio
Find fourth proportional to 1,380, 2,070 and 468
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.