Tutor MathsGuru: Ask me for your burning Maths questions!

[Tang]

Budo:

mathsguru:

[quote=\"Budo\"]Hi need help in this question


Andrew and Brian had some money
If Andrew gave Brian $55, the ratio of Andrew to Brian amount is 3:5.
If Brian gave Andrew 20% of this money and $10, Andrew would have $108 more than Brian.
How much do Andrew and Brian have at first?

:?

Hi Budo,

Here's my solution. Hope it helps!


MathsGuru

http://www.postimage.org/image.php?v=TstZYTJ

Thanks Maths Guru!!! $176 is the correct answer[/quote]
Hello,

There are multiple answers.

A -- 3u + $55
B -- 5u - $55

20% B -- 1/5 x (5u - $55) = 1u - $11
1u - $11 + $10 = 1u - $1

3u + $55 + 1u - $1 -- 4u + $54

5u - $55 - (1u - $1) -- 4u - $54

So condition of Difference of $108 is true regardless of value of 4u............

I believe there is a typo error - 'this' should be 'his'.

[liketoeat]

Please help me with this question. Thank you.


Najip, Kumar and Gurmit started jogging at the same time from the same starting-point round a circular track. Najip and Kumar jogged in a clockwise direction and Gurmit jogged in an anti-clockwise direction. Gurmit took 5 minutes to complete each round. Gurmit met Najip after every 3 minutes. Gurmit met Kumar after every 2 minutes. The jogging speed of each person remained the same throughout.

(a) What was the ratio of Gurmit’s speed to Najip’s speed to Kumar’s speed? (Ans: 6 : 4 : 9)
(b) When Gurmit and Najip met again at the starting-point after 15 minutes, Kumar had already jogged 3.6 km. What is the circumference of the circular track? (Ans: 0.8 km)

[liketoeat]

Here’s another question.


Each day, Mike saves $0.50 while Carol saves $0.30 more than her. Carol starts saving 6 days after Mike. She has $17.40 more than Mike now. How much does Mike save now? (Ans: $37)

[Dharma]

liketoeat:

Please help me with this question. Thank you.


Najip, Kumar and Gurmit started jogging at the same time from the same starting-point round a circular track. Najip and Kumar jogged in a clockwise direction and Gurmit jogged in an anti-clockwise direction. Gurmit took 5 minutes to complete each round. Gurmit met Najip after every 3 minutes. Gurmit met Kumar after every 2 minutes. The jogging speed of each person remained the same throughout.

(a) What was the ratio of Gurmit's speed to Najip's speed to Kumar's speed? (Ans: 6 : 4 : 9)
(b) When Gurmit and Najip met again at the starting-point after 15 minutes, Kumar had already jogged 3.6 km. What is the circumference of the circular track? (Ans: 0.8 km)

(a)
Time ratio => Najip : Gurmit = 3 : (5 – 3) = 3 : 2
Speed ratio => Najip : Gurmei = 2 : 3
Time ratio => Kumar : Gurmit = 2 : (5 – 2) = 2 : 3
Speed ratio => Kumar : Gurmit = 3 : 2

Speed ratio => Gurmit : Najip : Kumar = 6 : 4 : 9

(b)
When Gurmit and Najip met again in 15 mins (time is fixed)

Distance ratio => Gurmit :Najip : Kumar = 6 : 4 : 9
9u = 3.6km
1u = 0.4km

6u = 3 rounds ( 1 round = 5 mins; 3 round = 15 mins)
3 rounds = 6 x 0.4km = 2.4km
1 round = Circumference of track = 2.4km / 3 = 0.8km

[Dharma]

liketoeat:

Here's another question.


Each day, Mike saves $0.50 while Carol saves $0.30 more than her. Carol starts saving 6 days after Mike. She has $17.40 more than Mike now. How much does Mike save now? (Ans: $37)

Carol starts saving from Day 6 onwards.
Mike saved $ 3.00 ($0.50/day x 6 days) from Day 1 to Day 5

Day 6 to now; Carol saved $ 20.40 ($17.40 + $3.00) more than Mike.

No. of days from Day 6 to now = $20.40/ ($0.30/day) = 68 days

Amount Mike saved from Day 1 until now = $ 3.00 + ($0.50/day x 68 days) = $37.00

[Herbie]

I have one qn.


There were some boys and girls in a room.
If 24 boys leave the room, the total no. of students who remained in the room will be 7 times theno. of boys who remained the the room.
If 12 girls leave the room, the total no. of students who remained in the room will be 4 times the no. of boys.

How many students are there in the classroon?

Tq

[Dharma]

Herbie:

I have one qn.


There were some boys and girls in a room.
If 24 boys leave the room, the total no. of students who remained in the room will be 7 times theno. of boys who remained the the room.
If 12 girls leave the room, the total no. of students who remained in the room will be 4 times the no. of boys.

How many students are there in the classroon?

Tq

Boys at first = 1u + 24 = 1p ………… (1)
Girls at first = 6u = 3p + 12 ………… (2)

6u = 3(1u + 24) + 12
3u = 84
1u = 28

No. of students in classroom = 7u + 24 = 7(28 ) + 24 = 220

[Herbie]

Hi Dharma,


I dun understand how you form the eqn 1 and 2.

Can explain?

Tx

[livewith_vanilla]

Source: School Paper (P6)


Questions:

1) 65% of the animals on a farm were cows and the rest were goats. When 240 more cows and goats were added to the farm, the percentage of cows increased by 20% and the number of goats doubled. How many goats were there on the farm at first?

2)There are some black and white marbles in a bag.If 20 black marbles are removed from the bag, the total number of marbles left will be 7 times the number of black marbles left. If 50 white marbles are removed from the bag, the total number of marbles left will be 5 times the number of black marbles left.How many marbles are there in the bag?

TIA!

[Dharma]

Herbie:

Hi Dharma,


I dun understand how you form the eqn 1 and 2.

Can explain?

Tx

If 24 boys leave the room:

At last
Boys : 1u
Girls : 6u

At first
Boys : 1u + 24
Girls : 6u

If 12 girls leave the room

At last
Boys : 1p
Girls : 3p

At first
Boys : 1p
Girls : 3p + 12

The number of boys and girls at first must be the same

1u + 24 = 1p -------------- (1)
6u =3p + 12 --------------- (2)

Solve to find the no. of boys and girls