Camila and Lucíana bought the same mobile phone but in different places. Camila's had a value of 120,000 but they gave her a 30% discount, while Luciana had a value of 150,000 on which they applied a 40% discount Who paid less?

Camila paid less

Step-by-step explanation:

In the question, we are told:

Camila's phone had a value of 120,000 but they gave her a 30% discount.

Therefore, Camila paid:

30% × 120,000

= 30/100 × 120,000

= 36,000

Luciana had a value of 150,000 on which they applied a 40% discount

Luciana paid:

40% × 150,000

40/100 × 150,000

= 60,000

From the calculation,

Camila paid 36,000 and Luciana paid 60,000, therefore, Camila paid less.

9514 1404 393

  136

Step-by-step explanation:

The attached chart shows the result of using the numbers in the problem statement to calculate the percentage of the population in each category.

95% accuracy on infected individuals is assumed to mean that 95% of the 2% who are infected return a positive test result. The other 5% return a negative test result.

Similarly, 90% accuracy on uninfected individuals is assumed to mean that 90% of the 98% who are not infected will return a negative test result, and the remaining 10% of those 98% will return a (false) positive test result.

Then of the 11.7% who return a positive test result, only 1.9% are actually infected. This fraction is a/b = 19/117, so ...

  a + b = 19 + 117 = 136

_____

Additional comment

When forming ratios of percentages, one must be very clear about the base of the percentage. Above, the base for every percentage is the entire population of mathletes. The fraction 19/117 is the fraction of those who tested positive that are actually infected (about 16.2% of positives).