Let x be the number of defective cell phones. It is given that in batch of 100, on average 5 are defective.
let p be the probability of defective cell phone.
p = 5/100 = 0.05
Let n be size of random sample, n=30
Here out of 30 we want to find probability that 2 will be defective. It means 30-2 =28 cell phones will be non defective.
The probability of getting non defective cell phone is 1- p=1-0.05 =0.95
The probabability of getting 2 defective is
P(X=2) = number of ways selecting 2 from 30 * probability 2 defective * probability of 28 non defective
Now number of ways of selecting 2 cell phone from 30 is
30C2 =
=
=
= (30*29) /2
30C2 = 435
P(X=2) = 30C2 * (0.05)^2 * (0.95)^28
= 435 * 0.0025 * 0.2378
P(X=2) = 0.2586
Probability of getting 2 defective out of 30 is 0.2586
245 - 137 using a number line to answer your question write a number line from 0 to 245 and count back from 137 your welcome!!!!!!!!!!!
The volume of a cone can be found by using the equation V=(1/3)(pi*r^2*H). Given the information that H= 6cm and V= 8pi cm^3, the expression is 8pi=(1/3)(pi*r^2*6). (The second picture.)
Answer: The type is <u>Retrospective</u>.
Step-by-step explanation: Observational Study is a type of research which measures determined characteristics of a population by studying individuals in a sample, without interfering or influencing the variables. There are 3 types of observational study:
- Cross-sectional studies: colecting data at a certain point of time;
- Case-control studies: comparing individuals with a particular characteristics with others without it;
- Cohort studies: is the one where a group of individuals is selected to participate in the study;
According to the description given, the study above is a case-control study and the type is called <u>Retrospective</u> because it asks the individuals to tell about past habits, exposure to sunshine in this case. This type of study is not very reliable because it depends on the memory and the ability of the individuals to be honest and it can only prove association, not causation.