Home / 21,280-31,920-6,688

Finding the Fourth Proportional to 21,280, 31,920 and 6,688

Calculator

Solution

The fourth proportional to 21,280, 31,920 and 6,688 is: 10,032

Step by Step Solution

  1. Step 1: Write the proportion equation
    21,280 : 31,920 = 6,688 : x
  2. Step 2: Convert to fraction form
    21,280/31,920 = 6,688/x
  3. Step 3: Cross multiply
    21,280x = 31,920 × 6,688
  4. Step 4: Simplify right side
    21,280x = 213,480,960
  5. Step 5: Solve for x
    x = 213,480,960/21,280
  6. Step 6: Final answer
    x = 10,032

Related Problems

Find fourth proportional to 10,640, 15,960 and 3,344
Half scale
Find fourth proportional to 42,560, 63,840 and 13,376
Double scale
Find fourth proportional to 21,281, 31,921.50 and 6,689
Similar ratio
Find fourth proportional to 31,920, 47,880 and 10,032
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.