Q&A - P5 Math

[pineapple tarts]

Ms Tan bought some stationery. ½ of them were pens which cost 90¢ each. 1/3 of them were pencils which cost 50¢ each and the rest were erasers which cost 30¢ each. She spent $25.90 on the pens and pencils. How much did she spend on the erasers and stationery?

[pineapple tarts]

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.

[MathIzzzFun]

pineapple tarts:

Ms Tan bought some stationery. ½ of them were pens which cost 90¢ each. 1/3 of them were pencils which cost 50¢ each and the rest were erasers which cost 30¢ each. She spent $25.90 on the pens and pencils. How much did she spend on the erasers and stationery?

same approach as cheese and apple pies --> grouping

2 & 3 --> lowest common multiple = 6

For every group of 6 items:
3 pens --> 3 x $0.90 = $ 2.70
2 pencils --> 2 x $0.50 = $ 1.00
1 eraser --> 1 x $0.30 = $0.30
Total amount for each group --> $4.00
total for pens & pencils/group --> $3.70

Total spent on pens and pencils = $ 25.90
Number of groups = $ 25.90/$3.70 = 7

Amount spent on erasers = 7 x $0.30 = $ 2.10
Total amount spent on all stationery = 7 x $ 4.00= $ 28.00

cheers.

[MathIzzzFun]

pineapple tarts:

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
number of cookied is more than 126

List multiple of 9 and add 1,
we get: 127, 136, 145, 154...
remainder (in bracket) when divided by 7
--> 126 (1), 136 (3), 145 (5), 154 [0]

Look for remainder of 5 --> 145

Mrs Tan had 145 cookies.

cheers.

[pineapple tarts]

I need some time to digest the solution before I can explain to my DD. Thank you very much MathIzzzFun :salute:

[mathnoobs]

MathIzzzFun:

pineapple tarts:

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 ? :?

[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.