3 years ago

Don’t worry about the second question

Mathematics

1 answer:

matrenka [14]3 years ago

8 0

Answer:

Step-by-step explanation:

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A lot of 100 semiconductor chips contains 15 that are defective. three chips are selected at random from the lot without replace

Alex787 [66]

D=event that chip selected is defective
d=event that chip selected is NOT defective

Four possible scenarios for the first two selections:
P(DDD)=15/100*14/99*13/98=13/4620
P(DdD)=15/100*85/99*14/98=17/924
P(dDD)=85/100*15/99*14/99=17/924
P(ddD)=85/100*84/99*15/98=17/154

Probability of third selection being defective is the sum of all cases,
P(XXD)=P(DDD)+P(DdD)+P(dDD)+P(ddD)
=3/20

5 0

4 years ago

The area of a rectangle is 27 m^2 , and the length of the rectangle is 3 m less than twice the width. Find the dimensions of the

vagabundo [1.1K]

Let $L$ be the length of the rectangle and $W$ be the width. In the problem it is given that $L=2W-3$ . It is also given that the area $LW=27$ . Substituting in the length in terms of width, we have $W(2W-3)=27 \\ 2W^2-3W-27=0 \\ (2W-9)(W+3)=0$ . Using the zero product property, $2W-9=0 \text{ or } W+3=0$ . Solving these we get the width $W=4.5 \text{ or } -3$ . However, it doesn't make sense for the width to be negative, so the width must be $\boxed{4.5 \text{ m}}$ . From that we can tell the length $L=2(4.5)-3=\boxed{6 \text{ m}}$ .