Question

sarah spends $28 on food, this amount is 4/9 of his allowance. calculate his allowance

Answer 1

\[\frac{4}{9}x=28\]\[\frac{9}{4}28=x=$63\]

Answer 2

thank you

Answer 3

can you help in another question?

Answer 4

ok

Answer 5

a model of a car has a scale of 1:25. the model is 18cm long. calculate in metres the actual length of the car

Answer 6

If the model is 18cm and is 1/25th of size of the actual car, the actual car length is \[18cm*25=450cm\]That's more commonly shown as 4.5m.

Answer 7

In other words, if the scale is 1:25 then for every cm of model, there are 25 cm of actual car. Make sense?

Answer 8

yeah, i guess so

Answer 9

so its 4.5?

Answer 10

4.5m or 450cm...both are equivalent.

Answer 11

oh ok, 1 more

Answer 12

ok

Answer 13

camilla has $5 to spend in the market. she buys 1 and half kg of bananas priced at 80 cents per kg and 3 yams priced at 45 cents each. how much money does she have?

Answer 14

Well let's see.
For the bananas:\[\frac{0.80c}{kg}*1.5kg=$1.20\]For the yams: \[0.45c * 3 = $1.35\]\[$5-$1.35-$1.20=$2.45\]So she has $2.45 left.

Answer 15

i didnt get the banana part :S

Answer 16

you there?

Answer 17

I was answering another question. I'm back :)

Answer 18

ok :)

Answer 19

ok...let's see. What part didn't you understand about the bananas?

Answer 20

why we divided 0.80 over kg

Answer 21

That's just another way of writing the fact that the bananas are 0.80 center PER kg...the PER implies division.

Answer 22

err *cents

Answer 23

oh ok

Answer 24

We're not actually dividing the amount by "kg"...it's just a way of expressing the ratio. It also helps to keep the units straight later on when you take higher courses.

Answer 25

a block of cheese, of mass 8 kilograms, is cut by machine into 500 equal slices. calculate the mass of one slice of cheese in kg

Answer 26

Ok, you just need to divide the total mass by 500. What do you get?

Answer 27

what?

Answer 28

500 divide 8?

Answer 29

The block of cheese is 8kg...that's your total mass. You want to know the mass of one slice after you divide that block into 500 pieces. Mathematically, just divide 8 by 500.

Answer 30

i got it :)

Answer 31

\[\frac{8kg}{500}\]

Answer 32

ok :)

Answer 33

write in its simplest form, the ratio 3.5kg: 800 grams

Answer 34

we have to convert right?

Answer 35

Ok, now we're back to ratios. Remember when I said a ratio can be written as a fraction? Well, you can do the same thing here but first you need to convert one of the units to match the other. You either convert all the grams to kilograms or vice versa. I'll convert the grams to kilograms as follows:\[1kg = 1000g so 3.5kg = 3.5*1000=3500g\]
Now that out units are right, write the ratio as a fraction:\[\frac{3500g}{800g}=\frac{4.375}{1}\]The one on the right is in simplest form.

Answer 36

its 4.375:1?

Answer 37

Yep :)

Answer 38

my math teacher's gna be proud :P

Answer 39

What grade? Just curious

Answer 40

8th grade lol :{P

Answer 41

Well, trust me on this: Pay attention in math, science and english...those will get you the furthest in life :) The rest of the class....blah.

Answer 42

but math is REALLY hard, i got a 4.4/10 on my test, and most of the questions i got right were from my friend :/

Answer 43

Maybe you should get a tutor and practice more then. Math is the most useful class of all....but that's just my opinion.

Answer 44

yeah, i guess so :/

Answer 45

Getting better at math really just involves doing a lot of practice problems...that's the only way to learn it. It doesn't take a genius...just practice.

Answer 46

can you help me in one more question?

Answer 47

ok

Answer 48

it has 2 parts

Answer 49

ok

Answer 50

there are approximately 500,000 grains of wheat in 2kg of bag. a) calculate the mass of 1 grain in grams

Answer 51

That's just like the problem we did a moment ago. You have the total mass (2kg) and the number of pieces to break it into (500,000). What do you think you need to do?

Answer 52

divide?

Answer 53

Yes....go on

Answer 54

2/500,000?

Answer 55

Yes!

Answer 56

:D :D

Answer 57

What did you get?

Answer 58

4*10-6

Answer 59

That's correct...and you should know that it should be a very small value because you broke the 2kg into 500,000 pieces.

Answer 60

how do we right it not in standard form?

Answer 61

whole number

Answer 62

Since it's 10^-6 you have to move the decimal place 6 places to the left: 0.000004kg

Answer 63

but they said we have to write it in grams

Answer 64

No problem...how many grams are in a kilogram?

Answer 65

1000?

Answer 66

Yes...so multiply your answer times 1000.

Answer 67

0.000004*1000?

Answer 68

yes

Answer 69

4*10-3 is 0.0004?

Answer 70

0.004?

Answer 71

That's better :)

Answer 72

So it's 0.004 grams

Answer 73

:) thank you, i have to go do the rest of my homework :)

Answer 74

Ok, good luck!

Answer 75

thank you, bye