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[pokemon97]

can somebody help me solve this question?


The numbers of books Mrs Tee had is 4/5 the number of books Mrs Chua had. Mrs Tang had 60% fewer books than Mrs Tee. Mrs Tee and Mrs Chua gaveMrs Tang some books in the ratio of 3:2. As a result, Mrs Tand had 1 1/2 times as many books as before. Given that Mrs Chua had 261 books more than Mrs Tee in the end, how many books did Mrs Tee give to Mrs Tang?


Thanks

[Herbie]

can someone help to solve this burning maths qn?

The intensity of illumination, l lumen/m2, at a point on a screen is inversely proportional to the square of the dstance, d metre , ofthe light source fromthe point. Given that d=25m when l =0.8 lumen/m 2, find
A. l when d=1.25, my ans is 3.2 lumens/m2
B. d, when l=0.05 lumens/m2. My ans is 10

Are both answers correct?

[MathIzzzFun]

Herbie:

can someone help to solve this burning maths qn?

The intensity of illumination, l lumen/m2, at a point on a screen is inversely proportional to the square of the dstance, d metre , ofthe light source fromthe point. Given that d=25m when l =0.8 lumen/m 2, find
A. l when d=1.25, my ans is 3.2 lumens/m2
B. d, when l=0.05 lumens/m2. My ans is 10

Are both answers correct?

Hi

l is inversely proportional to square of the distance
so, l = k/d^2, where k is a constant.

at d= 25m, l = 0.8 = k/625, k = 500

now use l = 500/d^2 to find l and d for A and B, you should get
A. l = 320 lumens/square m
B. d = 100m

cheers.

[MathIzzzFun]

pokemon97:

can somebody help me solve this question?


The numbers of books Mrs Tee had is 4/5 the number of books Mrs Chua had. Mrs Tang had 60% fewer books than Mrs Tee. Mrs Tee and Mrs Chua gaveMrs Tang some books in the ratio of 3:2. As a result, Mrs Tand had 1 1/2 times as many books as before. Given that Mrs Chua had 261 books more than Mrs Tee in the end, how many books did Mrs Tee give to Mrs Tang?


Thanks

Hi

Tee : Chua = 4:5
Tang : Tee = 4:10 = 2:5
So, Tang : Tee : Chua = 8u: 20u : 25u

In the end, Tang had 1.5 times as many books
so, total number of books given by Tee and Chua = 0.5 x 8u = 4u

Tee gave 3/5 x 4u = 2.4u
Chua gave 2/5 x 4u = 1.6u

In the end,
Tee had 20u - 2.4u = 17.6u
Chua had 25u - 1.6u = 23.4u

Chua had 261 books more than Tee in the end,
23.4u - 17.6u = 261
5.8u = 261, 1u = 45

Mrs Tee gave 2.4u = 2.4 x 45 = 108 books to Mrs Chua

cheers.

[Herbie]

thanks mathsizzfun, sorry, i just dscovered i hv a topo error, d should be= 2.5m and not 25m.


Thanks for working it out for me! Many thanks!!

[Chan09]

Dear all, need some help on this:

B and C had a total of $1475 at first. After B spent 4/7 of his money and C spent $145. C found that the amt of money he had left was 5/6 of what B had left. How much more money had B than C at first?
Tks
And: $485

[MathIzzzFun]

Chan09:

Dear all, need some help on this:

B and C had a total of $1475 at first. After B spent 4/7 of his money and C spent $145. C found that the amt of money he had left was 5/6 of what B had left. How much more money had B than C at first?
Tks
And: $485

Hi

After B spent 4/7 of his money (ie 3/7 left) and C spent $145,
B: C = 6u : 5u
B's total = 7/3 x 6u = 14u
C's total = 5u + $145
B & C had total of $ 1475 at first --> 14u + 5u + $145 = $1475,
19u = $1330, 1u = $70

B-C = 14u - 5u - $ 145 = 9u - $145 = $630 - $ 145 = $485
B had $485 more than C at first.

cheers.

[2DMommy]

Dear all


Need help with these two questions :
1) Zach had a total of 2050 black and red marbles. He lost 3/5 of his black marbles and bought another 150 red marbles. As a result, the number of red marbles he had was 1/4 of the remaining black marbles. How many more black marbles than red marbles had he at first?\t

2) Vanessa, Hilton and Dolly were given a box of sweets. Vanessa took 1/3 of the sweets and another 20 from the box. Hilton took 0.5 of the remainder and another 40 from the box. Dolly took the remaining 30 sweets and there were no sweets left in the box.\t\t\t
a) How many sweets were there in the box at first ?\t\t\t
b) How many sweets did Hilton have finally ?\t

Thanks !

[MathIzzzFun]

2DMommy:

Dear all


Need help with these two questions :
1) Zach had a total of 2050 black and red marbles. He lost 3/5 of his black marbles and bought another 150 red marbles. As a result, the number of red marbles he had was 1/4 of the remaining black marbles. How many more black marbles than red marbles had he at first?\t

2) Vanessa, Hilton and Dolly were given a box of sweets. Vanessa took 1/3 of the sweets and another 20 from the box. Hilton took 0.5 of the remainder and another 40 from the box. Dolly took the remaining 30 sweets and there were no sweets left in the box.\t\t\t
a) How many sweets were there in the box at first ?\t\t\t
b) How many sweets did Hilton have finally ?\t

Thanks !

Hi

Q1

http://i53.tinypic.com/2vj4ozo.jpg\">

Q2 is a typical \"work backwards\" problem sum. For eg. start from the end, we have, 30 (by Dolly)+40 (by Hilton)= 70 =0.5 of \"last\" remainder Hilton took from, so last remainder = 2 x 70= 140 and then work back again to initial state.. give it a try !

cheers.


cheers.

[MathIzzzFun]

Herbie:

thanks mathsizzfun, sorry, i just dscovered i hv a topo error, d should be= 2.5m and not 25m.


Thanks for working it out for me! Many thanks!!

that's alright... u r welcome.

cheers.