Mathematics - 13 August 2007

The average of marks obtained by 240 students in an exam is 70, if average of passed students is 78 & average of failed students is 30, what is the number of students who passed in the exam? - please fetch me the answer with working i.e., the way to solve this...

2007-08-13 23:29:06 · 6 answers · asked by vinu 1

Okay I have a math exam (mock) tomorrow.. and I was doing revision when I had this question, I've never really got how to do this type of question (how to put the 1/2 into the brackets)...

My guess is:
y= ½ (x-4) (x+2)
y= ½x²-2x-2 Even if this is right once I get to here I don't know how to put it back in brackets without endless guess & checking...

When I put the equation into my graphics calculator it has the (x-4)(x-2) part with the x-intercepts at 4 and -2 but- Yay! I just just figured out how it works for GRAPHS. My caclulator has got the vertex at -4.5, half of the 3².... duh...

Hmm.. so I know how the graph works but I really don't get the equation, so my question still stands, how do you do an equation like this?
y= ½ (x-4) (x+2)

2007-08-13 22:57:08 · 5 answers · asked by Holly from NZ 2

I need to calculate a growth in numbers from 65 to 120, in a %.
I know that from 65 to 130 would be a 100% increase, but what is the growth from 65 to 120??? my mind just not working. please help

2007-08-13 22:47:50 · 10 answers · asked by victoria j 1

2007-08-13 22:37:22 · 5 answers · asked by akexyaya 1

Ninety people attended the school play. An adult ticket cost £5 and a childs one cost £3, and altogether they raised £320. Find out how many adults and how many children attended.

PLEASE TELL ME THE ANSWER AND THE WORKING.

Thank you. I always give best answer to the person who has the correct answer first.

2007-08-13 22:27:51 · 8 answers · asked by Hermione Granger 4

Please solve,

ln(x+2)*ln(x-2) = 0

* = times

2007-08-13 22:02:33 · 4 answers · asked by Anonymous

2007-08-13 22:01:39 · 4 answers · asked by old dick withers 3

2007-08-13 21:57:33 · 4 answers · asked by Peter 1

1. a) Find dy/dx of [(x/2)sqrt(16-(x^2))] + [8 sin^(-1) {x/4}]

b) Integrate | [sqrt(16-(x^2))] .dx

2007-08-13 21:48:42 · 2 answers · asked by year 12 student 2

4(3 - 2x) = 7x-4(1+x)

5-(8x-1) = 6(1-x)+2

2007-08-13 21:08:09 · 6 answers · asked by Hermione Granger 4

In New Zealand its world maths week & we have to go on website, answer quetsions etc. One question is particualy bugging me & I was wondering if someone could lend a helping hand...? Here it is:

This cipher appeared in an old Royal Air Force pocket book dated 1937. It is a transposition type cipher with a message asking for help.

What is the message?

How many more men need to be sent?

AMVIPI WWYRHI VVITEM VXASHE CWLIEH QERWIG VIXPCM RXIVJI VMRKAS VOSRPE RHMRKK VSYRHW IRHXIR QSVIQI RZZZZZ





Thank you!

2007-08-13 20:25:42 · 3 answers · asked by Anonymous

Use the definition of the derivative to find the derivative of:
a) -(2/3x)

b) (sq. rt.2x) - x^3

2007-08-13 20:06:17 · 5 answers · asked by Allison 1

A) C= pie d if C=42 d=?

B) A=L*B if A=54 L=6.5 B=?

C) y=mx+b y=14 x=3 b=-7 m=?

2007-08-13 19:15:17 · 6 answers · asked by Anonymous

A) (18a)^0 G)3y^2 multiply 2y^0

B) 3c multiply 4cd

C) (2 divivde5)^5

E) x^b multiply x^c

F)14x^3y^5 divide7x^2y^2

2007-08-13 18:56:10 · 3 answers · asked by Anonymous

same blood contain?

2. It is known that making 1lb. of honey requires 20,000 trips by bees to flowers to gather nectar. How many pounds of honey would 65,000 trips produce?

3. Last season a major league baseball player got 140 hits in 200 times at bat. If the player expects to bat 500 times in the entire season with the same ratio of hits to at bats, how many hits can the player expect to have?

4. A sample of 142 firecrackers contained 5 duds. How many duds would you expect in a sample of 2698 firecrackers?

5. Find the variation constant and an equation of variation where y varies directly as x and y=54 when x=6

2007-08-13 18:48:14 · 2 answers · asked by Anonymous

Will you help me with this geometry question, please?
Thank you a bunch.
And show/explain how to get the result?

An astronaut is tethered to the corner of a solid cube with edges of length 50 (on the outside) by a rope of length 10. Assuming there is no gravity, what is the volume of the space in which the astronaut is free to roam?

Thanks a bunch. <3

2007-08-13 18:47:26 · 3 answers · asked by eirhya 1

Prove by induction that, for a =/ 1 (a NOT EQUAL to 1)

1+a+a^2+...+a^n = (a^n-1)/(a-1)

If someone can please help its much appreciated. Need full working out

Don

2007-08-13 18:47:08 · 5 answers · asked by Anonymous

same blood contain?

2. It is known that making 1lb. of honey requires 20,000 trips by bees to flowers to gather nectar. How many pounds of honey would 65,000 trips produce?

3. Last season a major league baseball player got 140 hits in 200 times at bat. If the player expects to bat 500 times in the entire season with the same ratio of hits to at bats, how many hits can the player expect to have?

4. A sample of 142 firecrackers contained 5 duds. How many duds would you expect in a sample of 2698 firecrackers?

5. Find the variation constant and an equation of variation where y varies directly as x and y=54 when x=6

2007-08-13 18:38:10 · 4 answers · asked by Anonymous

Let P(x)= X^4+6X^2+9

A. Find All Zero of P(x)

B. Factor P(x) Completely



PLease Help...thank so much

2007-08-13 18:17:06 · 6 answers · asked by cc_jason_cc 2

How long will it take for the object to hit the ground?

2007-08-13 18:02:26 · 4 answers · asked by Anonymous

I figured out that the top is -3 +/- (sqrt)14. At lease I think. But now I am stuck from here

2007-08-13 17:58:04 · 3 answers · asked by Anonymous

I'm totally lost (I have only one week to learn Grade 11 Trig) because of this summer course and I need all the help I can get.

My teacher doesn't explain nearly enough...if anyone can direct me to where I can find some easy to understand help on right triangle trig, tri functions of any angle, law of sines and cosines.....or if there any any experts here willing to help a poor gal out on MSN I would be so grateful.

girl.inspired@yahoo.ca

Please help, thank you!

2007-08-13 17:46:49 · 2 answers · asked by Rebirth _2007 1

HELP

2007-08-13 17:43:42 · 2 answers · asked by Anonymous

If a radius bisects a chord, then are the lengths of the parts of the radius on either side of the chord equal?

Does the definition of a chord prove this?

2007-08-13 17:30:03 · 3 answers · asked by ems 2

Please help me with this one. you have to solve the differential equation.

1. dy/dx=( y^2 + xy^2) / (x^2y - x^2)

2007-08-13 17:19:13 · 5 answers · asked by Anonymous

31X + 12Y - 24Z = 105

18X + 24Y + Z = 77

12X - 6Y + 4Z = 5

2007-08-13 16:59:51 · 2 answers · asked by Anonymous

I have the velocity reading in an 8 inch pipe and want to convert this to a flow rate in cubic feet per minute. Thanks.

2007-08-13 16:40:13 · 7 answers · asked by Anonymous

Can't figure these out, please help.

4. Suppose X and Y be independent normal random variables, with distributions N(μ, sigm) = N(5, 3) and N(2, 4) respectively. Let W = X + 2Y + 1.
Compute
(a) E(W); (b) V (W); (c) Prob(W < 0) (d) Cov(X,W) .
5. Suppose that X and Y are rv’s which only assume the values 0 and 1. Suppose that the joint pmf p(x, y) satisfies p(0, 0) = .3, p(0, 1) = .4, p(1, 0) = .2.
(a) What is p(1, 1)?
(b) Compute E(2X − Y ).
(c) Are X and Y independent?
(d) Compute the conditional pmf pX(x).
6. Suppose that the number of phone calls Tara receives in the evening is a Poisson process with rate 2 per hour, and the number of calls I receive is an independent Poisson process with rate 0.1 per hour.
(a) At 6 p.m., Tara returns home and happily waits for her next
phone call. What is the probability that she will get a call before 7:30 pm?
(b) What is the probability that at least one of us receives at least one phone call between 6 and 7:30 pm?

2007-08-13 16:25:37 · 2 answers · asked by Anonymous

solve the equation.. show work!!


1) |4x-9|= -4


2) x+1 - 2 {x+11} = 0 { }= square root symbol..since there isnt one on the keyboard!!

Thanks!

2007-08-13 16:23:39 · 6 answers · asked by sexycheerleader2009 3

Will you help me with this geometry question, please?
Thank you a bunch.
And show/explain how to get the result?

What is the area of a 13 by 14 by 15 triangle?

Thanks a bunch. <3

2007-08-13 16:18:49 · 9 answers · asked by eirhya 1