Q&A - P5 Math

[MathIzzzFun]

mathnoobs:

MathIzzzFun:

Hi again,


This one look so simple but I can't get the correct anwser. Hope u can help.

Mrs Tan has more than 120 cookies. If she put them into packets of 7, she has 5 cookies left. If she puts them in packet if 9, she has 1 cookie left. What is the least nos. of cookies Mrs Tan has?

Thank you.

One approach --> listing, with a slight twist:

7 & 9 --> lowest common multiple = 63
Possible number will lie between 63 & 126

List multiple of 9 and add 1,
we get: 64, 73, 82, 91, 100, 109, 118
divide by 7, find remainder (in bracket)
--> 64 (1), 73 (3), 82 (5), 91 (0), 100 (2), 109 (4), 118 (6)

Look for remainder of 5 --> 82

Mrs Tan had 82 cookies.

cheers.

I don't quite understand this.
Mrs Tan should have more than 120 cookies.
Based on this criteria, the next number in line after 82, with a remainder of 5 should be 145. Or am I wrong in this ? :?

Oops.. misread question.
Multiple of 9 + 1:
127, 136, 145, 154..

remainder (in brackets)when divided by 7:
127(1), 136 (3), 145 (5), 154 (0)

mrs tan had 145 cookies.

cheers.

[bookwormkids]

Hi, need some help.


P5 SA2 2007 Ai Tong
Q42
Bobby, Edward and Kelvin made a bottle of paper stars. The number of paper stars Bobby made was 21 more than 1/4 the total number of paper stars in the bottle. The number of paper stars Edward made was 30 more than 1/4 of the remaining number of paper stars in the bottle. Kelvin made the remaining 114 paper stars. How many paper stars did they make in all?

Q43
A, B and C are three numbers. The average of A, B and C is 5 greater than the average of A and B. If C is 38, find the total of A, B and C.

P5 SA2 2009 Ai Tong
Q12
Siti had some money. She gave some money to Kelly and Lindy and saved the rest. The ratio of her savings to the amount she gave away was 5: 8. The ratio of Kelly's money to Lindy's money was 5: 3 at first. After Kelly's money increased by $128 and Lindy's money decreased by $128, the ratio of Kelly's money to Lindy's money became 3: 1. How much money did Siti save?

Thanks!

[enreachlearningcentre]

[quote]Hi, need some help.


P5 SA2 2007 Ai Tong
Q42
Bobby, Edward and Kelvin made a bottle of paper stars. The number of paper stars Bobby made was 21 more than 1/4 the total number of paper stars in the bottle. The number of paper stars Edward made was 30 more than 1/4 of the remaining number of paper stars in the bottle. Kelvin made the remaining 114 paper stars. How many paper stars did they make in all?

Q43
A, B and C are three numbers. The average of A, B and C is 5 greater than the average of A and B. If C is 38, find the total of A, B and C.

P5 SA2 2009 Ai Tong
Q12
Siti had some money. She gave some money to Kelly and Lindy and saved the rest. The ratio of her savings to the amount she gave away was 5: 8. The ratio of Kelly's money to Lindy's money was 5: 3 at first. After Kelly's money increased by $128 and Lindy's money decreased by $128, the ratio of Kelly's money to Lindy's money became 3: 1. How much money did Siti save?

Thanks! [/quote]Hi, please refer to the attached pic. Q42 &Q12 best illustrated by models. Q43 by algebra. Hope it helps! http://i50.tinypic.com/r6xzlf.jpg\"> http://i49.tinypic.com/2rwx7ww.jpg\">

[ajmum]

Need help for this question.

Mr Lim bought 4 pears and 5 lemons. Mr Tan bought 5 pears and 4 lemons. Mr Tan paid 0.20 more than Mr Lim. If Mr Lim paid $4.40, how much did 4 pears cost ?

Thank you so much.

[charsen]

ajmum:

Need help for this question.

Mr Lim bought 4 pears and 5 lemons. Mr Tan bought 5 pears and 4 lemons. Mr Tan paid 0.20 more than Mr Lim. If Mr Lim paid $4.40, how much did 4 pears cost ?

Thank you so much.

Hi
4pears+5Lemons=$4.40
5pears+4Lemons=$4.60
9pears+9lemons=$9
1Pear+1lemon=$1
$1x4=$4
Cost of 1 lemon-->$4.40-$4.00=$0.40
Cost of 1 Pear-->$1-0.40=0.60
Cost of 4 pears-->0.60x4=$2.40(ANS)
Cheers

[ajmum]

Thanks charsen .


Need help for another 2 questions,

1. There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first.

2. Grandma had some yellow and purple sweets in the ratio of 9:7. On Monday, she made 54 more yellow sweets. On Tuesday, she gave away 44 purple sweets and sold 129 yellow sweets. The number of yellow sweets to number of purple sweets became in the ratio of 6:5. How many yellow sweets are there in the end ?

Thank you for help.

[MathIzzzFun]

ajmum:

Thanks charsen .


Need help for another 2 questions,


2. Grandma had some yellow and purple sweets in the ratio of 9:7. On Monday, she made 54 more yellow sweets. On Tuesday, she gave away 44 purple sweets and sold 129 yellow sweets. The number of yellow sweets to number of purple sweets became in the ratio of 6:5. How many yellow sweets are there in the end ?

Thank you for help.

http://www.flickr.com/photos/62167097@N02/7069963797/in/photostream

using MD:

http://i50.tinypic.com/2jfhutk.png\">

cheers.

[MathIzzzFun]

ajmum:

Thanks charsen .


Need help for another 2 questions,

1. There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first.

Thank you for help.

http://i50.tinypic.com/2jbseo6.png\">

cheers.

[MathIzzzFun]

bookwormkids:

Hi, need some help.


P5 SA2 2007 Ai Tong
Q42
Bobby, Edward and Kelvin made a bottle of paper stars. The number of paper stars Bobby made was 21 more than 1/4 the total number of paper stars in the bottle. The number of paper stars Edward made was 30 more than 1/4 of the remaining number of paper stars in the bottle. Kelvin made the remaining 114 paper stars. How many paper stars did they make in all?


Thanks!

Q42.
Work backwards

It would be good to draw a simple diagram or model - I will not put up one here due to time constraint.

Total = Bobby's stars + Remainder 1 --- Bobby's stars = 1/4 Total + 21
Remainder 1 = Edward's stars + Remainder 2 --- Edward's stars = 1/4 of Remainder 1 + 30
Remainder 2 = Kelvin's stars = 114

Remainder 1 = Edward's stars + 114 = 1/4 of Remainder 1 + 30 + 114
3/4 Remainder 1 = 144
Remainder 1 --> 144/3 x 4 = 192

Total = Bobby's stars + Remainder 1 = 1/4 Total + 21 + 192
3/4 Total = 213
Total --> 213/3 x 4 = 284

They made 284 altogether.

cheers.

[MathIzzzFun]

bookwormkids:

Hi, need some help.


P5 SA2 2007 Ai Tong
Q43
A, B and C are three numbers. The average of A, B and C is 5 greater than the average of A and B. If C is 38, find the total of A, B and C.


Thanks!

http://i50.tinypic.com/35d68mq.jpg\">

cheers.