you need to prepare 180g of a 5% cream using 30% stock cream and a cream base.how much needed of each?

You want to dilute the 30% cream by 30/5 = 6 times so you want 1 part of the 30% cream + 5 parts of the base. How much is 1 part? That's 180/6 = 30 g = 1 part.

5 parts base = 5*30 = 150 g = 5 parts
Total = 6 parts = 180g.

To find out how much of each component you need, we can use the principle of molarity.

Let's assume x represents the amount of stock cream needed in grams, and y represents the amount of cream base needed in grams.

Step 1: Convert the given percentages to decimals by dividing by 100:
30% = 0.30
5% = 0.05

Step 2: Set up an equation based on the amount of cream:
x + y = 180g

Step 3: Set up an equation based on the amount of active ingredient (cream):
0.30x + 0y = 0.05(180g)

Step 4: Solve the equations simultaneously:
x + y = 180
0.30x = 0.05(180)

Simplifying the second equation:
0.30x = 9
Divide both sides by 0.30:
x = 30

Substitute the value of x into the first equation:
30 + y = 180

Solve for y:
y = 180 - 30
y = 150

Therefore, you need 30g of the 30% stock cream and 150g of the cream base to prepare 180g of a 5% cream.