happynanny03

The average life-time of 500 light bulb is advertised as lasting as 1200 hours with a standard deviation of 150 hours. Assuming that the life-time is normally distributed, answer the followings:

a) Find the probabilty that any bulb randomly selected from the above sample will have life-time

i. between 1065 and 1365 hours

ii. more than 1450 hours

iii. between 980 and 1000 hours

b) Find the respective number of bulbs of the life-time given in part a).

limit ( 4x^2 - x - 1 ) / (x -1)

x->1

how to get solution for this question?

i tried these:-

x=0.9, f(x)= -13.4

x=0.99, f(x)= -193.04

x=0.999, f(x)= -1993.004

x=1.001, f(x)= 2007.004

x=1.01, f(x)= 207.04

x=1.1, f(x)= 27.4

anyone can guide me on this?

Which of the following has the same number of atoms as in 1 mole of ammonia gas?

[Relative atomic mass: H, 1; C, 12; N, 14; O, 16; Al, 27]

A. 2.5 moles of oxygen gas

B. 1.5 moles of water

C. 3 moles of aluminium

D. 4/3 moles of carbon dioxide

ANSWER: D

Can anyone show me how to get the answer please?

Thank you so much!

One-fifth of those taking a mathematics course are also taking a computer science course, and one-eight of those taking a computer science course are also taking a mathematics course. If the number of students who only taking mathematics course is 50, find the number of the students who are taking

(a) mathematics course

(b) mathematics and computer science courses

(c) mathematics or computer science courses.

A box stored in a warehouse contain 100 identical parts, of which 10 are defective and 90 are non defective. Three parts are selected without replacement. Find the probability that

(a) state the sample space

(b) at most one part is defective

(c) the last selection is non defective

(d) the three parts are non defective

A shipment of grapefruit arrived containing the following proportions of types: 10% pink seedless, 20% white seedless, 30% pink with seeds, 40% white with seeds. A grapefruit is selected at random from the shipment. Find the probability that

(a) it is seedless

(b) it is pink and seedless

(c) it is pink and seedless

(d) it is pink, given that is it seedless

(e) it is seedless, given that it is pink

I'm unsure with what does it want me to answer. Please help me....

Below is a sample of one-way commute time, to the nearest minute, for 50 college students who are gainfully employed.

2 10 3 5 1 19 14 3 15 12

30 10 2 8 19 17 12 29 21 29

15 23 3 24 4 16 49 15 64 5

3 22 19 1 48 4 25 7 22 4

3 10 33 12 14 30 10 13 5 23

a) Construct a frequency distribution table of these data.

How to construct? by using lower limit and upper limit or what? I'm confuse.

b) Construct a suitable graph from (a)

Is it histogram??

c) Find the mean, mode, median, Q1 and Q3

I know how to do this.

d) Find the three measures of dispersion.

Is it range, variance and standard deviation?

e) Using graph and calculation above to write a short report that you believe best describes the typical employed college student’s commute to work.

what am i suppose to report on? the mean time for student to travel? i have no idea on this part..

Please help me if you know how to do this, thanks.

If 80% of the people in a community have Internet access from their homes, find these probabilities for a sample of 10 people.

(a) At most 6 have Internet access.

(b) Exactly 6 have Internet access.

(c) At least 6 have Internet access.

(d) Which event, a, b or c is most likely to occur? Explain why.

Which of the following are binomial experiments or can be reduced to binomial experiments?

(a) Surveying 100 people to determine if they like Sudsy Soap.

(b) Testing 4 different brands of aspirin to see which brands are effective.

(c) Testing one brand of aspirin to determine whether it is effective.

(d) Asking 100 people if they smoke.

(e) Surveying 300 prisoners to see whether this is their first offence.

I can't differentiate them..

Can tell me the reasons as well? Thanks.

du tracteur, un agriculteur de 40 ans, est décédé. Parmi les 220 passagers du train, seule une femme enceinte a été légèrement blessée. Une enquête a été ouverte pour déterminer les circonstances de l'accident

sorry to write in english.

my friend send me this message,

and i think something happened to him.

anyone can tell translate or tell me what is written above ?

thanks..

du tracteur, un agriculteur de 40 ans, est décédé. Parmi les 220 passagers du train, seule une femme enceinte a été légèrement blessée. Une enquête a été ouverte pour déterminer les circonstances de l'accident

Anyone can translate this phrase to english please???

my friend leave me this message, and i guess maybe he got involved in accident...

If y^2 = C [(x-4)/(x+5)] where C is a constant, find the differential equation by eliminating the constant C. [ans: dy/dx = 9y/2y(x+4)] But i get another extra (x+5) in the denominator, can anyone help me to check whether the provided answer is correct or mine is correct?

Q: If y = ( cos x )^1/2 , show that 4y^3(d2y/dx2) + y^4 +1 = 0

Finally i have figure it out but not sure whether is it acceptable or not..

y = ( cos x )^1/2

y^2 = cos x

diff. w.r.t x,

2y(dy/dx) = - sin x

diff. w.r.t x,

2y(d2y/dx2) + 2(dy/dx)^2 = - cos x

2y(d2y/dx2) + 2[( - sin x ) / ( 2y )]^2 = -y^2 (since (dy/dx) = [- sin x / 2y ] and y^2 = cos x, so i sub. it here)

2y(d2y/dx2) + [( sin^2 (x) ) / ( 2y^2 )] = -y^2

4y^3(d2y/dx2) + sin^2 (x) = -2y^4

Since y^2 = cos (x), so,

y^4 = cos^2 (x)

And using trigonometry identity,,

sin^2 (x) + cos^2 (x) = 1

sin^2 (x) = 1 - cos^2 (x)

= 1 - y^4

So,

4y^3(d2y/dx2) + 1 - y^4 = -2y^4

4y^3(d2y/dx2) + y^4 + 1 = 0

So it's proven. Can be accept or not ?

Q: What is the product of ( - sin x / 2y )^2 ?

Is it ( sin^2 (x) / 4y^2 ) ?

Q: If y = ( cos x )^1/2 , show that 4y^3(d2y/dx2) + y^4 +1 = 0

Sorry that just now post the wrong question. This is the correct question, anyone can guide?

Q: If y = ( cos x )^1/2 , show that 4y^3(dy/dx) + y^4 +1 = 0

.

I can't solve it, anyone can guide me please?