Q&A - P5 Math
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Hello again,
One more to trouble you guys.
In a school hall, a certain nos. of students can be arranged such that there are exactly 21 students per row. If the same nos. of students is arranged in rows of 16 students each, there will be 7 more rows and 8 students left over. How many students are there altogether?
Thank you in advance. -
pineapple tarts:
When arranged in rows of 16,Hello again,
One more to trouble you guys.
In a school hall, a certain nos. of students can be arranged such that there are exactly 21 students per row. If the same nos. of students is arranged in rows of 16 students each, there will be 7 more rows and 8 students left over. How many students are there altogether?
Thank you in advance.
\"excess\" students from rows of 21 --> 16 x 7 + 8 = 120
these come from \"removing\" 5 from original rows of 21, so
rows of 21 --> 120/5 = 24
Number of students --> 24 x 21 = 504
cheers. -
pineapple tarts:
Each cheese pie --> $6Hello Maths guru,
Need your help on this question.
Mary bought 5 times as many cheese pie as apple pie for a party. She paid a total of $165. Each cheese pie costs twice as much as the apple pie. If each cheese pie costs $6, how many cheese pie and apple pie did she buy?
Thank you.
Each apple pie --> $3
Cost of 1 group of 5 cheese pies + 1 apple pie
= 5 x $6 + $3 = $33
Number of groups --> $165/$33 = 5
Mary bought:
cheese pies --> 5 x 5 = 25
apple pies --> 5 x 1 = 5
cheers. -
Dear MathIzzzFun
:thankyou: -
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?
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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. -
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. -
pineapple tarts:
One approach --> listing, with a slight twist: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.
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. -
I need some time to digest the solution before I can explain to my DD. Thank you very much MathIzzzFun :salute:
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MathIzzzFun:
I don't quite understand this.
One approach --> listing, with a slight twist: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.
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.
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 ? :?