David rolls a number cube fifty times. The number 4 comes up twelve times. The number 3 comes up eight times. What is the experimental probability of rolling a 3 or 4? *
1 point
20%
30%
40%
50%

40%.

Step-by-step explanation:

Prob( Rolling a 4) = 12/50

Prob( Rolling a 3) = 8/50

When the combined probabilities contain  an 'OR' we Add the probability values:

Probability of a 3 or a 4  

= 12/50 + 8/50

= 20/50

= 2/5

= 40%.

the formula for converting absorbance to transmittance goes as:

a = log (1/t)  a = 2 - log(%t)  10^a = 1/t  t = 10^-a  %t = 100(10^-a)

so at the given value of a,   a = 1.5

%t = 100(10^-1.5)

%t = 3.16%