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

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)
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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.

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

We can do it using mixtures concept..

65 _____100
___75___
25_____10

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

Answer: A

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

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

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
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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
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