# Maths

Watch
Announcements
#1
I need help with this question:
20) There are only red sweets and yellow sweets in a bag.
There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
He says that the probability that the sweet will be red is
7/10(a) Show why the probability cannot be
7/10
0
2 months ago
#2
(Original post by raidas0001)
I need help with this question:
20) There are only red sweets and yellow sweets in a bag.
There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
He says that the probability that the sweet will be red is
7/10(a) Show why the probability cannot be
7/10
2/10 ,because 8/10 + 2/10 = 10/10 ,since the 10 in the denominator reveals the number of candies in the bag as a whole
0
2 months ago
#3
although this question involves sweets, it should not really be in the Food and Drink forum

2
2 months ago
#4
(Original post by raidas0001)
I need help with this question:
20) There are only red sweets and yellow sweets in a bag.
There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
He says that the probability that the sweet will be red is
7/10(a) Show why the probability cannot be
7/10
0
2 months ago
#5
I thought under 13s weren't allowed on TSR?
0
2 months ago
#6
(Original post by lucydales)
2/10 ,because 8/10 + 2/10 = 10/10 ,since the 10 in the denominator reveals the number of candies in the bag as a whole
No, that's not correct
0
#7
(Original post by Muttley79)
n/(n+8)=7/10
10n=7n+56
3n=56
n=18.66666666666666
if the probability of getting red is 7/10 then there is a decimal number of red sweets and u can't have 0.6666666667 of a sweet.
i am not sure if i'm correct
0
2 months ago
#8
(Original post by raidas0001)
n/(n+8)=7/10
10n=7n+56
3n=56
n=18.66666666666666
if the probability of getting red is 7/10 then there is a decimal number of red sweets and u can't have 0.6666666667 of a sweet.
i am not sure if i'm correct
Yep, looks good.

I'd reword it slightly, since in general all numbers are decimal (it just means base 10).

If the probabilty of getting a red is 7/10, then there must be 18 2/3 sweets. Since the number of sweets must be a whole number it follows you can't get a probability of getting a red being 7/10 .
0
2 months ago
#9
(Original post by Muttley79)

After Sajid has taken the first sweet from the bag and eaten it, he is going to take at random a second sweet from the bag. Given that the probability that both the sweets he takes will be red is 3/5.

Work out the number of red sweets in the bag.
0
2 months ago
#10
(Original post by raidas0001)
I need help with this question:
20) There are only red sweets and yellow sweets in a bag.
There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
He says that the probability that the sweet will be red is
7/10(a) Show why the probability cannot be
7/10
The reason why it can't be 7/10 is that then the number of sweets wouldn't be whole and that does not make sense to have something like half a candy.

If the probability of a red sweet is 7/10 then the probability of a yellow sweet is 3/10 meaning that the number of total sweets will be 8*10/3 which is 26 3/4. This doesn't make sense as mentioned before, non-whole numbers don't make sense.
0
2 months ago
#11
(Original post by raidas0001)
I need help with this question:
20) There are only red sweets and yellow sweets in a bag.
There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
He says that the probability that the sweet will be red is
7/10(a) Show why the probability cannot be
7/10

After Sajid has taken the first sweet from the bag and eaten it, he is going to take at random a second sweet from the bag. Given that the probability that both the sweets he takes will be red is 3/5.

Work out the number of red sweets in the bag.
0
2 months ago
#12
Nope, you need an algebraic explanation for that create a simple expression from teh info given to you and you will realise you just do not get a whol enumber
Last edited by Fiaraziqbal; 2 months ago
0
1 month ago
#13
what exam paper is this question from?
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

Yes (96)
27.51%
No (253)
72.49%