Q&A - P5 Math

[chloecube]

May spent all her money on 5 shirts and 3 blouses. each blouse cost $7 less than each shirt. if she bought 3 shirts and 2 blouses instead, she would have $56 left. what was the cost of a blouse?

[jieheng]

chloecube:

May spent all her money on 5 shirts and 3 blouses. each blouse cost $7 less than each shirt. if she bought 3 shirts and 2 blouses instead, she would have $56 left. what was the cost of a blouse?

1 Blouse --> 1u
1 Shirt -----> 1u + 7

5 shirts and 3 blouses --> 5*(1u + 7) + 3*(1u) = 8u + 35

3 shirts and 2 blouses --> 3*(1u + 7) + 2*(1u) = 5u + 21

(8u + 35) - (5u + 21) --> 56
3u + 14 --> 56
3u --> 42
1u --> 14

the cost of a blouse was $14

[chloecube]

jieheng:

chloecube:

May spent all her money on 5 shirts and 3 blouses. each blouse cost $7 less than each shirt. if she bought 3 shirts and 2 blouses instead, she would have $56 left. what was the cost of a blouse?

1 Blouse --> 1u
1 Shirt -----> 1u + 7

5 shirts and 3 blouses --> 5*(1u + 7) + 3*(1u) = 8u + 35

3 shirts and 2 blouses --> 3*(1u + 7) + 2*(1u) = 5u + 21

(8u + 35) - (5u + 21) --> 56
3u + 14 --> 56
3u --> 42
1u --> 14

the cost of a blouse was $14

thank you

[acehkr3009]

Hi, I have come across this P5 question & will like to know if there is any other ways of solving it instead of using model/graphical…Thks in advance:


6A & 6B have the same number of pupils each. The ratio of the number of boys in 6A to the number of boys in 6B is 1:3. The ratio of the number of girls in 6A to the number of girls in 6B is 4:1. What is the ratio of the number of girls to the number of boys in 6B?

[Suz855]

acehkr3009:

Hi, I have come across this P5 question & will like to know if there is any other ways of solving it instead of using model/graphical...Thks in advance:


6A & 6B have the same number of pupils each. The ratio of the number of boys in 6A to the number of boys in 6B is 1:3. The ratio of the number of girls in 6A to the number of girls in 6B is 4:1. What is the ratio of the number of girls to the number of boys in 6B?

You can use the concept of constant difference

Boys
A:B : diff
1:3 : 2
3 : 9 : 6

Girls
A:B : diff
4:1 : 3
8:2 : 6

6B
G : B
2 : 9
:oops:

[acehkr3009]

Hi Suz855…thks

[S-H]

Hi, can someone please help me with this question, thank you!


There are 30 questions in a mathematics competition. 5 marks are awarded for each question answered correctly. 3 marks are deducted for each wrong answer. Ben scored 118 marks for this competition. How many questions did he get wrong?

[tianzhu]

S-H:

Hi, can someone please help me with this question, thank you!


There are 30 questions in a mathematics competition. 5 marks are awarded for each question answered correctly. 3 marks are deducted for each wrong answer. Ben scored 118 marks for this competition. How many questions did he get wrong?

Hi S-H

You may use “Make a Supposition/Assumption concept”

If Ben got all his answers correct, he would get (30*5) or 150 marks.

150 – 118 ----- 32

One wrong answer costs (5 + 3) or 8 marks

Number of wrong answers ------- 32/8 ------- 4

Best wishes

[S-H]

tianzhu:

S-H:

Hi, can someone please help me with this question, thank you!


There are 30 questions in a mathematics competition. 5 marks are awarded for each question answered correctly. 3 marks are deducted for each wrong answer. Ben scored 118 marks for this competition. How many questions did he get wrong?

Hi S-H

You may use “Make a Supposition/Assumption concept”

If Ben got all his answers correct, he would get (30*5) or 150 marks.

150 – 118 ----- 32

One wrong answer costs (5 + 3) or 8 marks

Number of wrong answers ------- 32/8 ------- 4

Best wishes

Thank you tianzhu, but I still don't understand why one wrong answer is 8 marks and not 3 marks which was stated in the question??

[tianzhu]

S-H:

tianzhu:

Thank you tianzhu, but I still don't understand why one wrong answer is 8 marks and not 3 marks which was stated in the question??

Hi S-H

Right answer ----- plus 5 marks

Wrong answer ----- minus 3 marks

Difference between a right and wrong answer ------ 8 marks

Best wishes