A perfect cake should have 25% cream and 75% bread. Oman bought materi

Question

A perfect cake should have 25% cream and 75% bread. Oman bought material for a 5kg cake with 35% cream and 65% bread. How many more kg of bread should he buy if he wants to make a perfect cake?

A. 2kg
B. 2.5kg
C. 3kg
D. 4kg
E. 5kg

eabhgoy · Accepted Answer

5 kg material has been bought with 35% cream and 65% bread
=> Amount of cream = 35% of 5 kg = 1.75 Kgs
=> Amount of bread = 65% of 5 kg = 3.25 Kgs (Another way would be 5-1.75 = 3.25Kgs)

Now we want to convert the ratio from 35%-65% to 25%-75% by buying more bread.
Here the amount of cream remains constant, hence 1.75kgs of cream should be 25% of the total amount.
Hence we need to have 75% of the bread. Now 75% is 3 times 25%, therefore the amount of bread we should have is 3 times the amount of cream

=> 3*1.75 = 5.25 kgs of bread is required

We have 3.25 kgs of bread and hence require 2 extra kgs of bread.

Hence A is the correct answer.

KarishmaB · Answer

Of the 5 kgs he has bought, 35% is cream.
Cream = 35/100 * 5 = 7/4 kg
Bread = 5 - 7/4 kg = 13/4 kg

The ratio of Cream:Bread should actually be 25:75 = 1:3 so bread should be 3*(7/4) kg = 21/4 kg. 
So he should buy another 21/4 - 13/4 = 8/4 = 2 kg of bread.

Answer (A)

Archit3110 · Answer

5kg has 35% cream or say ; 5*35/100 ; 7/4
and bread 5*65/100 ; 13/4

perfect cake ratio ; 25:75 ; 1:3
so 3*7/4 ; 21/4
kg of bread required ; 21/4-13/4 ; 8/4 ; 2kgs
IMO A

pravalithota · Answer

We can do it using mixtures concept..

65 _____100
 ___75___
25_____10

x=(5/25)*10
 =2kg

Answer: A

kitipriyanka · Answer

perfect cake has 75% bread i.e. 3/4 ratio
Now current has 65% bread, now say we add x% to make ratio 3/4
Therefore, 65+x/100+x=3/4
x=40
hence 40% more needs to be added.
Now 40% of 5kg= 2kg
Hence A

AnirudhaS · Answer

35% of 5 kg=1.75 kg cream
65% of 5 kg=3.25 kg bread
Let the required amount of bread to be added be x kg
so,  \frac{1.75}{3.25+x}=\frac{25}{75} 
or, x = 2 kg

Answer:  A

Shrey08 · Answer

Note that only the percentage of bread is to be increased.

Cream --- 35% of 5kg =  \frac{7}{4}  Kg (This is a fixed quantity)

For a perfect cake we need 25% Cream and 75% Bread

This  \frac{7}{4}  Kg of cream is 25% of what quantity ?

25% of X =  \frac{7}{4}

\frac{1}{4}  of X =  \frac{7}{4}

X = 7 Kg

We already have 5 Kg of cake material we need 2Kgs more. 
We need 2Kgs more bread to make a perfect cake.
 Option A

adityasuresh · Answer

A perfect cake should have 25% cream and 75% bread. Oman bought material for a 5kg cake with 35% cream and 65% bread. How many more kg of bread should he buy if he wants to make a perfect cake?

A. 2kg
B. 2.5kg
C. 3kg
D. 4kg
E. 5kg

I used weighted average:
A1 = 65
A2 = 100
Aavg = 75
W1 = 5
W2 = ?
 Weight of bread + weight of cream/Weight of bread  =  5/w2  = 100 - 75/75-65  
 5/w2  =  25/10  = 10 = 5w2 = w2 = 2
 A

avadana · Answer

Dear pravalithota

Please explain what 100 denotes in above solution. My understanding from above is that in order to get average of 75 from two different entities of 65 and 100, we need 25 units of former and 10 units of latter.

Shin0099 · Answer

The easiest solution should be the following:

We calculate the weight of the current cream and multiply it by 4, because we assume, it must be 1/4 of the final total. That will give is the result of the total material. The difference of New total - Old total will give us the final result. 
That means:
5*35% = 1.75
1.75*4 = 7
7 - 5 = 2
We need two additional KGs of material, which are by definition of the question bread.

A

VidhiJ · Answer

Why are we allowed to assume that the final cake can weigh more than 5 kg?  My instinct was to treat the 5 kg as the final weight.

If the final cake must still weigh 5 kg, then:
Required bread = 5×0.75=3.755 	imes 0.75 = 3.755×0.75=3.75 kg
He already has 5×0.65=3.255 	imes 0.65 = 3.255×0.65=3.25 kg

So he would only need 0.5 kg more bread, provided we also remove some cream

Bunuel · Answer

I see your point and agree the wording could have been clearer. However, the question asks how much more bread he should buy, not how to adjust the existing 5 kg into a perfect 5 kg cake. Adding bread increases the total weight, and the question never states that the final cake must still weigh 5 kg.

A perfect cake should have 25% cream and 75% bread. Oman bought materi

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