Question 5

x = 8

To solve the proportion 0.8:10 :: x:100, we can use cross-multiplication. This leads to the equation 0.8 * 100 = 10 * x, which simplifies to x = 8.

A) x = 0.8

This option is incorrect because substituting 0.8 into the proportion would not maintain the equality. In the original proportion, 0.8 relates to 10, and if x were 0.8, the relationship with 100 would not hold true.

B) x = 80

This choice is also incorrect. If x were 80, then using the same cross-multiplication method would give a false relationship, as it would imply a much larger relationship than the original proportion of 0.8 to 10.

C) x = 800

This option is incorrect as well. If x were 800, the proportion would skew significantly, indicating an unrealistic relationship compared to the original ratio of 0.8:10.

D) x = 8

This option is correct. By cross-multiplying the original proportion, we find that x must equal 8 to maintain the equality established by the ratio 0.8:10 compared to x:100.

Conclusion

The correct answer, x = 8, accurately reflects the proportional relationship defined by the original ratio. All other options fail to satisfy the equality derived from cross-multiplication, confirming that only option D maintains the integrity of the proportion presented.