Answer:
Step-by-step explanation:
We know that the standard quadratic equation is ax^2+bx+c=0
Let's compare all the given equation to it and , find discriminant.
1. a=2, b= -7, c=-9
So it has 2 real number solutions.
2. a=1, b=-4, c=4
So it has only 1 real number solution.
3. a=4, b=-3, c=-1
So it has 2 real number solutions.
4. a=1, b=-2, c=-8
So it has 2 real number solutions.
5. a=3, b=5, c=3
Thus it does not has real solutions.
Answer:
Option: C is the correct answer.
C. Buying a needle and buying thread are dependent events.
Step-by-step explanation:
let A denotes the events of buying a thread.
and B denote the event of buying a needle.
Then A∩B denote the event of buying a needle and a thread.
Also let P denote the probability of an event.
i.e. we are given:
P(A)=0.15
Also P(B|A)=0.25
As we know that:
As we know that when two events A and B are independent then,
P(A∩B)=∅
otherwise they are dependent events.
Hence, option: C is the correct answer.
Step-by-step explanation:
In statistics, the empirical rule states that for a normally distributed random variable,
In mathematical notation, as shown in the figure below (for a standard normal distribution), the empirical rule is described as
where the symbol (the uppercase greek alphabet phi) is the cumulative density function of the normal distribution,
is the mean and
is the standard deviation of the normal distribution defined as
.
According to the empirical rule stated above, the interval that contains the prices of 99.7% of college textbooks for a normal distribution ,
Therefore, the price of 99.7% of college textbooks falls inclusively between $77 and $149.
