Another pri 5 maths qns

[Hamburger]

pls help cos i am helpless...

 

john bought some table lamps and the average costs of lamp was $52. When he bought another table lamp which cost $70, the average costs then became $54. What was the total number of table lamp she had in the end?

 

please provide me with workings too....thks

[Friendstar]

Can use algebra? Cos if use algebra really easy

[Hamburger]

no....p5 no algebra...

[Lon3fly3r]

sry 4got pri5 cannot use this. ps

 

 

-edited out-

Edited October 27, 2011 by Lon3fly3r

[Requiemdk]

$70 - $54 = $16, the excess cost which gets distributed over the rest of the lamps to raise up the average. This raises the old average by $2, so there were $16/$2 = 8 lamps to begin with. You can draw boxes to represent the lamps I guess...

[Ethene]

no. of lamp = x

total cost of all lamp = 52x

 

after adding the last $70 lamp:

 

(52x + 70) / (x + 1) = 54

2x = 16

x = 8 (Ans)

 

[VenomMX]

no. of lamp = x

total cost of all lamp = 52x

 

after adding the last $70 lamp:

 

(52x + 70) / (x + 1) = 54

2x = 16

x = 8 (Ans)

 

U use algebra in p5 arh?

[Hamburger]

errrr.................

 

answer is 9. But i no idea how it arrives....

[VenomMX]

$70 - $54 = $16, the excess cost which gets distributed over the rest of the lamps to raise up the average. This raises the old average by $2, so there were $16/$2 = 8 lamps to begin with. You can draw boxes to represent the lamps I guess...

 

Yes, this answer is suitable for p5 level.. Just have to draw model like bro requiemdk said

[VenomMX]

$70 - $54 = $16, the excess cost which gets distributed over the rest of the lamps to raise up the average. This raises the old average by $2, so there were $16/$2 = 8 lamps to begin with. You can draw boxes to represent the lamps I guess...

 

8 to begin with.. But questions asks how many FINALLY.. so 8+1 la.. U got your 9

[VenomMX]

errrr.................

 

answer is 9. But i no idea how it arrives....

 

Most students will miss out the last step of adding the 1 new lamp.. Thats why must teach them to read the question properly

[Hamburger]

thks bro for the answer.

 

if i am born 30yrs younger, confirm eat strength.......

[VenomMX]

thks bro for the answer.

 

if i am born 30yrs younger, confirm eat strength.......

 

No prob bro.. I give tuition to pri sch kids part time so im glad to help u out.. Wait till your kid is p6.. Some questions can really make u go

Haha

[Sg2303]

pls help cos i am helpless...

 

john bought some table lamps and the average costs of lamp was $52. When he bought another table lamp which cost $70, the average costs then became $54. What was the total number of table lamp she had in the end?

 

please provide me with workings too....thks

 

I think P5 should be using GUESS and CHECK method

 

 

Edited October 27, 2011 by Sg2303

[VenomMX]

I think P5 should be using GUESS and CHECK method

 

 

No of lamps Average price Total price New lamp New total New average

 

5 52 260 70 330 55 wrong

 

6 52 312 70 382 54.57 wrong

 

7 52 364 70 434 54.25 wrong

 

8 52 416 70 486 54 correct

 

Yes bro thats correct.. Guess and check method is 100% acceptable as well

[Leeke1]

pls help cos i am helpless...

 

john bought some table lamps and the average costs of lamp was $52. When he bought another table lamp which cost $70, the average costs then became $54. What was the total number of table lamp she had in the end?

 

please provide me with workings too....thks

X=initial total cost of Lamp

Y=initial total lamp

 

X/Y=52

X=52Y

(X+70)/(Y+1)=54

(52Y+70)/(Y+1)=54

Y=8

Total lamp at the end is Y+1=9

Ans is 9

[Sg2303]

 

I've been a part time private tutor for pri/sec students since Uni days.

[Helios467]

wah piangz eh........

 

:o