Astudent is taking an exam consisting of three questions selected randomly from a list of 100 questions. to pass, he needs to answer all three questions. what is the probability that the student will pass the examination if he knows the answers to 90 questions on the list?

The probability that the student will pass is 72.6%

Step-by-step explanation:

There are 100 questions total.

The order that the questions are selected makes no diffence. For example, if  Q3, Q28, Q57 are selected in this order or as Q28, Q57, Q3, it is the same exam. So it is a combination problem.

Combination Formula:

A combination of n elements from a set of m objects has the following formula:

Probability:

The probability is the number of desired outcomes divided by number of total outcomes.

The number of total outcomes is the combination of 3 questions from a set of 100 questions. So, we have n = 3, m = 100.

There are 161700 total outcomes.

The number of desired outcomes is the combination of 3 questions from a set of 90 questions(the questions that the student knows the answers). So, we have n = 3, m = 90.

Probability P = D/T = 117480/161700 = 0.726 = 72.6%

The probability that the student will pass is 72.6%

the inequality is:

250c+180g≥950

step-by-step explanation:

let c denotes the number of days in a week   miyoko worked as a cryptographer.

and g denotes the number of days in a week she works as a geologist.

now we are given that she earns $250 for every day she works as a cryptographer,and earns $180 for every day she works as a geologist.

now miyoko's goal is to earn more than $950 this week.

hence, the inequality could be represented as:

250c+180g≥950

don't report but were is the digram

step-by-step explanation: