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RUDIKE [14]
3 years ago
11

Ted needs an average of at least 70 on his three history test he has scored already 85 and 60 on two test what is the minimum gr

ade ted need on his third test?
Mathematics
1 answer:
PilotLPTM [1.2K]3 years ago
4 0
So average=(total of scores)/(number of tests)
needs at least average of 70
at least is represented as greater than or equal to or the sign (<u>></u>)
70<u>></u>(total)/(number oftests)

since we have 3 tests, we have to have 3 scores so
70<u>></u>(x+y+z)/3
he scored 85 and 60
70<u>></u>(x+85+60)/3 (doesn't matter which to subsitute)
70<u>></u>(x+145)/3
multiply obht sides by 3
210<u>></u>x+145
subtract 145 from both sides
65<u>></u>x
he needs to get at leas 65 on his third test





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The lifetime of a certain type of battery is normally distributed with mean value 15 hours and standard deviation 1 hour. There
KIM [24]

Answer:

If the lifetime of batteries in the packet is 40.83 hours or more then, it exceeds for 5% of all packages.

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 15

Standard Deviation, σ = 1

Sample size = 4

Total lifetime of 4 batteries = 40 hours

We are given that the distribution of lifetime is a bell shaped distribution that is a normal distribution.

Formula:

z_{score} = \displaystyle\frac{x-\mu}{\sigma}

Standard error due to sampling:

\displaystyle\frac{\sigma}{\sqrt{n}} = \frac{1}{\sqrt4} = 0.5

We have to find the value of x such that the probability is 0.05

P(X > x)  = 0.05

P( X > x) = P( z > \displaystyle\frac{x - 40}{0.5})=0.05  

= 1 -P( z \leq \displaystyle\frac{x - 40}{0.5})=0.05  

=P( z \leq \displaystyle\frac{x - 40}{0.5})=0.95  

Calculation the value from standard normal z table, we have,  

\displaystyle\frac{x - 40}{0.5} = 1.64\\x = 40.825 \approx 40.83  

Hence, if the lifetime of batteries in the packet is 40.83 hours or more then, it exceeds for 5% of all packages.

8 0
3 years ago
Mrs.Barkley has 75 feet ribbon. If each of the 18 students in her class gets an equal length of ribbon, how many inches of ribbo
Black_prince [1.1K]

Answer:

Each student would get 4 inches of ribbon


Step-by-step explanation:

Mrs. Barkley has 75 inches of ribbon and is splitting it between 18 students so you would divide 75 by 18. When you divide you get 4.166666... etc. So the answer would be 4

3 0
3 years ago
Find the length AB round your answer to the tenth
Kobotan [32]

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

AB =  \sqrt{ ({3 - ( - 2)})^{2} +  ({4 - 0})^{2}  }  \\

AB =  \sqrt{ ({3 + 2})^{2} +  {4}^{2}  }

AB =  \sqrt{ {5}^{2} +  {4}^{2}  }

AB = \sqrt{25 + 16}

AB = \sqrt{41}

AB = 6.403

AB = 6.4

♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️

3 0
3 years ago
What is 22 + 5d = -8(7d-4)
ratelena [41]

22+5d=-8x7d=56d+ -8x-4=32

22+5d=-56d+32

22+32=54 and -56d+5d=-51d

The answer would be 51d+54

4 0
3 years ago
Read 2 more answers
Please help me I don’t understand this at all
ZanzabumX [31]

A, C, and D are the answers.

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3 years ago
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