All categories

3 years ago

I need help with this question. Question in image. Show working out to answer

Mathematics

2 answers:

Andreyy893 years ago

7 0

Answer:

Step-by-step explanation:

taurus [48]3 years ago

7 0

20 (boys) the mean was 62% so times that by 20 it will give me 1240 marks.

After that do 30x70 so number of students times the 70% mean which gives 2100.

Now take the 2100 - 1240 = 860.

After that 860/10 = 86%

20 boys get 62 and 10 girls get 86 this all will equal to 2100.....2100/30 = 70

So the final answer is 86%

You might be interested in

Twice the difference of a number and eight equals two

sdas [7]

Answer:

10-8=2 i think

Step-by-step explanation:

5 0

3 years ago

Since opening night, attendance at Play A has increased steadily, while attendance at Play B first rose and then fell. Equations

nexus9112 [7]

Answer: option d is correct .

Step-by-step explanation:

In order to find the same attendance we set both equation equal

8x+191 = -x^2+26x+126

simplifying equation ,we get

x^2 -18x+65=0

(x-5) (x-13) = 0

x =5 or x =13

therefore on 5th day and 13th day both plays attendance is same

and it is obtained by plugging x = 5 in and x =13 in either of the equation.

for x = 5 ,

y = 8(5) +191 = 40+191 = 231

for x = 13

y = 8(13)+191

= 104+191

= 295

therefore option d is correct

4 0

4 years ago

The resting heart rate of an adult is usually about 60 beats per minute. Use your completed table to find approximately how many

Fofino [41]

if 60 beats = 1 minute, and a minute is 60 seconds then 1,000,000 beats has to be divided by 60 = 16667 rounded to the nearest hundred thousand and divide that by 1440 (How many seconds in a day) = 11.574 days.

That equates to 11days, 13hours, 46 min, and 40 sec

4 0

3 years ago

Put in order from least to greatest 12, 8, -9, -12, 10, 16 *

Nina [5.8K]

Answer:

-12,-9,8,10,12,16

Step-by-step explanation:

3 0

3 years ago

Read 2 more answers

The manager of a computer retails store is concerned that his suppliers have been giving him laptop computers with lower than av

34kurt

Answer:

Probability that the 50 randomly selected laptops will have a mean replacement time of 3.1 years or less is 0.0092.

Yes. The probability of this data is unlikely to have occurred by chance alone.

Step-by-step explanation:

We are given that the replacement times for the model laptop of concern are normally distributed with a mean of 3.3 years and a standard deviation of 0.6 years.

He then randomly selects records on 50 laptops sold in the past and finds that the mean replacement time is 3.1 years.

Let M = sample mean replacement time

The z-score probability distribution for sample mean is given by;

Z = $\frac{ M-\mu}{\frac{\sigma}{\sqrt{n} } }} }$ ~ N(0,1)

where, $\mu$ = population mean replacement time = 3.3 years

$\sigma$ = standard deviation = 0.6 years

n = sample of laptops = 50

The Z-score measures how many standard deviations the measure is away from the mean. After finding the Z-score, we look at the z-score table and find the p-value (area) associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X.

Now, Probability that the 50 randomly selected laptops will have a mean replacement time of 3.1 years or less is given by = P(M $\leq$ 3.1 years)

P(M $\leq$ 3.1 years) = P( $\frac{ M-\mu}{\frac{\sigma}{\sqrt{n} } }} }$ $\leq$ $\frac{ 3.1-3.3}{\frac{0.6}{\sqrt{50} } }} }$ ) = P(Z $\leq$ -2.357) = 1 - P(Z $\leq$ 2.357)

= 1 - 0.99078 = 0.0092 or 0.92%

So, in the z table the P(Z $\leq$ x) or P(Z < x) is given. So, the above probability is calculated by looking at the value of x = 2.357 in the z table which will lie between x = 2.35 and x = 2.36 which has an area of 0.99078.

Hence, the required probability is 0.0092 or 0.92%.

Now, based on the result above; Yes, the computer store has been given laptops of lower than average quality because the probability of this data is unlikely to have occurred by chance alone as the probability of happening the given event is very low as 0.92%.

8 0

4 years ago