Home / 991.92-1,369.47-638

Finding the Fourth Proportional to 991.92, 1,369.47 and 638

Calculator

Solution

The fourth proportional to 991.92, 1,369.47 and 638 is: 880.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.92 : 1,369.47 = 638 : x
  2. Step 2: Convert to fraction form
    991.92/1,369.47 = 638/x
  3. Step 3: Cross multiply
    991.92x = 1,369.47 × 638
  4. Step 4: Simplify right side
    991.92x = 873,721.86
  5. Step 5: Solve for x
    x = 873,721.86/991.92
  6. Step 6: Final answer
    x = 880.84

Related Problems

Find fourth proportional to 495.96, 684.74 and 319
Half scale
Find fourth proportional to 1,983.84, 2,738.94 and 1,276
Double scale
Find fourth proportional to 992.92, 1,370.85 and 639
Similar ratio
Find fourth proportional to 1,487.88, 2,054.21 and 957
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.