## Q&A - P5 Math

### Re: Q&A - P5 Math

Tap Y can fill an empty tank in 6 minutes. When Tap Y and Tap Z are turned on at the same time, they can fill the empty tank in 4 minutes. How long does it take for Tap Z to fill the empty tank?

Is the answer 12 minutes?

Is the answer 12 minutes?

- speedmaths.com
- BrownBelt
**Posts:**559**Joined:**Mon Oct 12,**Total Likes:**3

### Re: Q&A - P5 Math

Hi,BigDevil wrote:Tap Y can fill an empty tank in 6 minutes. When Tap Y and Tap Z are turned on at the same time, they can fill the empty tank in 4 minutes. How long does it take for Tap Z to fill the empty tank?

Is the answer 12 minutes?

Yes, 12 mins.

**speedmaths**

### Re: Q&A - P5 Math

I am very sorry that I still don't understand!quekcc wrote:note that area of triangle CFG = area of triangle CFE.ttlkbs wrote:Can you explain the logic behind? Thanks a million!Maths Tutor Mr. Lim wrote:96/2 - 20 = ans

triangles with common base or height

Maths, make it easy!

and area of triangle CFE + area of triangle ADF = half of area of rectangle ABCD.

So 96/2 - 20 = 28.

### Re: Q&A - P5 Math

Can you please explain how to get 12min? thanks.speedmaths.com wrote:Hi,BigDevil wrote:Tap Y can fill an empty tank in 6 minutes. When Tap Y and Tap Z are turned on at the same time, they can fill the empty tank in 4 minutes. How long does it take for Tap Z to fill the empty tank?

Is the answer 12 minutes?

Yes, 12 mins.

speedmaths

- Nebbermind
- KiasuGrandMaster
**Posts:**16632**Joined:**Tue Dec 22,**Total Likes:**168

### Re: Q&A - P5 Math

Y fills 1/6 of the tank in 1 minLaurel111 wrote:speedmaths.com wrote:Hi,BigDevil wrote:Tap Y can fill an empty tank in 6 minutes. When Tap Y and Tap Z are turned on at the same time, they can fill the empty tank in 4 minutes. How long does it take for Tap Z to fill the empty tank?

Is the answer 12 minutes?

Yes, 12 mins.

speedmaths

Can you please explain how to get 12min? thanks.

Y+Z fill 1/4 of the tank in 1 min

Therefore Z fills (1/4-1/6) = 1/12 of the tank in 1 min

Z needs 12 mins to fill whole tank.

### Re: Q&A - P5 Math

Stuck... Help please.. Thanks in advance

**A store sells pens in packs of 2s (small) and 4s (big).**

At first there were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?At first there were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?

### Re: Q&A - P5 Math

quekcc wrote:note that area of triangle CFG = area of triangle CFE.ttlkbs wrote:Can you explain the logic behind? Thanks a million!Maths Tutor Mr. Lim wrote:96/2 - 20 = ans

triangles with common base or height

Maths, make it easy!

and area of triangle CFE + area of triangle ADF = half of area of rectangle ABCD.

So 96/2 - 20 = 28.

**note that area of triangle CFG = area of triangle CFE.**

Can explain in details please, also dont understand ... Thanks

### Re: Q&A - P5 Math

quekcc wrote:The triangle CFG and CFE have the same base CF, and the same height (as point G and point E are on the rectangle, so perpendicular height is the same. Well not necessary rectangle, as long as the points lies on the line parallel to the base).

As formula of area of triangle is 1/2 x base x height, so area of triangle CFG = area of triangle CFE.

In fact, this is a property to be remembered when study area of rectangle and triangle.

and area of triangle CFE + area of triangle ADF = half of area of rectangle ABCD.

So 96/2 - 20 = 28.