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blsea [12.9K]
3 years ago
15

Kyle has three short straws, four medium straws, and six long straws. If he randomly draws two straws, one at a time without rep

lacement, what is the probability that both are short straws?
Mathematics
1 answer:
max2010maxim [7]3 years ago
8 0
Total number of straws is 13.

P(both are short) = (3/13(2/12)

P(both are short) = 6/156

P(both are short) = 1/26
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A motorboat travels 168 kilometers in 4 hours going upstream. It travels 280 kilometers going downstream in the same amount of t
Grace [21]

Answer:

The speed of the boat is 56 km/hr

The rate of the current is 14 km/hr

Step-by-step explanation:

We are given the following;

  • Distance traveled upstream = 168 km
  • Time taken to travel upstream = 4 hours
  • Distance traveled down stream = 280 km
  • Time taken down stream = 4 hours

We are required to determine the speed of the boat in still water and the speed of the current.

We are going to take;

Speed of the boat as = x km/hr

Rate of flow of current = y km/hr

We can determine the speed of the boat upstream;

Speed = Distance ÷ time

               = 168 km ÷ 4 hours

               = 42 km/hr

But, the speed upstream is given by (x - y) km/hr

Therefore; ( x-y) km/hr = 42 km/hr ......................... Eqn 1

Speed of the boat down stream

    speed = 280 km ÷ 4 hours

                = 70 km/hr

But, the speed downstream is given by (x+y) km/hr

Therefore, x+y km/hr = 70 km/hr ........................... Eqn 2

Solving Eqn 1 and Eqn 2 simultaneously;

x - y = 42

x + y = 70

Eliminating x

-2y = - 28

    y = 14 km/hr

Solving for x,

x = 42 + y

   = 42 + 14

   = 56 km/hr

Therefore, the speed of the boat is 56 km/hr while the rate of the current is 14 km/hr

8 0
4 years ago
A random sample of 100 people from City A has an average IQ of 120 with a SD of 18. Independently of this, a random sample of 15
Sloan [31]

Answer:

z=\frac{(120-116)-0}{\sqrt{\frac{18^2}{100}+\frac{15^2}{150}}}}=1.837

p_v =P(z>1.837)=1-P(Z  

Comparing the p value with a significance level for example \alpha=0.05 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can say that the average IQ on city A is signficantly higher than city B at 5% of singificance.  

Step-by-step explanation:

\bar X_{A}=120 represent the mean for sample 1

\bar X_{B}=116 represent the mean for sample 2

s_{A}=18 represent the sample standard deviation for 1  

s_{B}=15 represent the sample standard deviation for 2  

n_{A}=100 sample size for the group 2  

n_{B}=150 sample size for the group 2  

\alpha Significance level provided

z would represent the statistic (variable of interest)  

Concepts and formulas to use  

We need to conduct a hypothesis in order to check if residents of City A smarter on average, the system of hypothesis would be:  

Null hypothesis:\mu_{A}-\mu_{B}\leq 0  

Alternative hypothesis:\mu_{A} - \mu_{B}> 0  

We don't have the population standard deviation's, but the sample sizes are large enough we can apply a z test to compare means, and the statistic is given by:  

z=\frac{(\bar X_{A}-\bar X_{B})-\Delta}{\sqrt{\frac{s^2_{A}}{n_{A}}+\frac{s^2_{B}}{n_{B}}}} (1)

z-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

With the info given we can replace in formula (1) like this:  

z=\frac{(120-116)-0}{\sqrt{\frac{18^2}{100}+\frac{15^2}{150}}}}=1.837

P value

Since is a one right tailed test the p value would be:  

p_v =P(z>1.837)=1-P(Z  

Comparing the p value with a significance level for example \alpha=0.05 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can say that the average IQ on city A is signficantly higher than city B at 5% of singificance.  

5 0
3 years ago
The sum of a number and twice another number is 17. The sum of twice the first number and the second number is 4. What are the t
zhannawk [14.2K]

Step-by-step explanation:

Given that,

a + 2b = 17

Also,

2a + b = 4

By adding the above expressions we get,

a + 2b + 2a + b = 17 + 4

3a + 3b = 21.

3 (a + b) = 21

a + b = 21/3

a + b = 7 Let us take 'b' = 10

a + 10 = 7

a = 7 - 10

a = -3

Now let's check by verifying by putting a = -3 and b = 10 in the previous expressions

a + 2b = 17

-3 + (2 × 10) = 17

-3 + 20 = 17

17 = 17

2a + b = 4

(2 × -3) + 10 = 4

-6 + 10 = 4

4 = 4

Therefore, a = -3 and b = 10 [(-3,10)] is the solution.

8 0
3 years ago
One half of an apple pie is left for
vlada-n [284]

Answer: It will be 2/10

Step-by-step explanation:because if you divide the half part that you have into five and the other one two you will have 10 pieces that divided into 5 members will be 2

8 0
3 years ago
Plz help me and show work this is worth 25points
andrezito [222]
The answers are..
6. 55
7. 6
8. 39
9. 17
8 0
3 years ago
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