Question

rainy day occurs once in every 10 days. Half of the rainy days produce rainbows. What percent of all
the days do not produce rainbow ?

Answer 1

Given:

the rainy day occurs once in every 10 days. Half of the rainy days produce rainbows.  

To find:

What per cent of all the days do not produce rainbow?

Solution:

Let the total number of days = x

From given, we have,

the rainy day occurs once in every 10 days.  

Therefore, the number of rainy days = x/10

Number of days with rainbows = 1/2 × x/10 = x/20

Number of days without rainbows = x - x/20 = 19x/20

The per cent of all the days with no rainbows = [(19x/20)/x] × 100% = 95%

∴ The per cent of all the days with no rainbows  is 95 %