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sergiy2304 [10]
3 years ago
15

4/5 of the 315 members of a book club are male.How many female members are there in the club?

Mathematics
1 answer:
Pavel [41]3 years ago
7 0
213 because

4/15 * 315 = 84 male <span>
11/15 * 315 = 231 female 

</span>
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What number fall between the square root of 180
zvonat [6]
It will fall betwenn the square root of 169 which is 13 and 196 is 14
7 0
3 years ago
The life times of light bulbs produced by a particular manufacturer have a mean of 1,200 hours and a standard deviation of 400 h
Nezavi [6.7K]

Answer:

a. 1200hours

b.  σ² = 400² =160000hour

c. standard error = 133.33

d. for 9 lightbulb it is likely that 9*0.146 = 1.31 bulbs will have lives of fewer than 1,050 hours?

Step-by-step explanation:

mean of 1,200 hours

σ, a standard deviation of 400 hours.

Sample size, N =  nine bulbs,

a) mean of the sample mean lifetime: is given as 1,200 hours

b) variance of the sample mean is the square of the  σ, a standard deviation of 400 hours.

σ² = 400² =160000hours

c) What is the standard error of the sample mean?

The standard deviation of a sampling distribution of mean values is called the standard error of the means,

standard error of the means,  σx = σ √N

The formula for the standard error of the means is true for all values infinite number of sample, N.

σx = σ √N

     =400  √9 = 400/3 =133.3333

d) the probability that, on average, those nine lightbulbs have lives of fewer than 1,050 hours

The area under part of a normal probability curve is  directly proportional to probability and the value is calculated as

z = ( x₁−x) /σ

where z = propability of normal curve

x₁ = variate mean = 1050hours

x = mean of 1200hours

σ = standard deviation = 400

applying the formula,

z= (1050-1200)/400

z = 150/400 =0.375

Using a table of partial areas beneath the standardized normal curve (see Table of normal curve, a z-value of 0.375 corresponds to an area of 0.1460 between the mean value.

Thus the probability of a lightbulbs having lives of fewer than 1,050 hours is 0.1460.

for 9 lightbulb it is likely that 9*0.146 i.e. 1.31 bulbs will have lives of fewer than 1,050 hours?  

8 0
3 years ago
Does anyone know how to change their username for Brainly????? If so HELP!!!!!!!!!! Will give 20 points to anyone I really don't
Len [333]

Answer:

no I don't is it not in the user settings?

8 0
2 years ago
Read 2 more answers
I will give brainliest fast please I will give points please explain well
ANEK [815]

If the equal is 55x + 35y = 200

x: time-driven at 55 miles/hour

y: time-driven at 35 miles/hour

If the car spends 2.5 hours at 35 miles per hour, then it drove:

 55x + 35(2.5) = 200

    55x =35

       y = 112.5

There the drive spent about 2.5-hour driving at 55 mph.

Hope it helps!

4 0
2 years ago
.<br> Evaluate the series 1 + 0.1 + 0.01 + . . .
EastWind [94]

We can employ a simple repeated decimal trick:

x=1.111\ldots

0.1x=0.111\ldots

\implies x-0.1x=1\implies0.9x=1\implies x=\dfrac1{0.9}=\dfrac{10}9

###

Alternatively, we can compute the partial sum of the series.

\displaystyle S_n=\sum_{k=0}^n\dfrac1{10^k}

S_n=1+0.1+0.01+\cdots+\dfrac1{10^n}

0.1S_n=0.1+0.01+0.001+\cdots+\dfrac1{10^{n+1}}

\implies S_n-0.1S_n=0.9S_n=1-\dfrac1{10^{n+1}}

\implies S_n=\dfrac{10}9-\dfrac9{10^n}

As n\to\infty, the second term vanishes and we're left with \dfrac{10}9. Notice that this is really just a more formal version of the earlier trick.

6 0
3 years ago
Read 2 more answers
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