Justin needs 15 L of a 22% sodium hydroxide (NaOH) solution for an experiment he is running. Unfortunately, the laboratory only has 30% NaOH and 5%
NaOH in stock. How many liters of each sodium hydroxide solution does Justin need to
mix to make the 15 L for his experiment?

Quantity of 30% NaOH = 10.2 L .

Quantity of 5% NaOH =4.8L .

Step-by-step explanation:

Let x = Quantity of 30% NaOH .

y= Quantity of 5% NaOH .

As per given, x+y= 15         (i)[total quantity]

0.30x+0.05y=0.22(15)     [quantity of NaOH]

⇒ 0.30x+0.05y=3.3    (ii)

Multiply 0.30 to (i), we get

0.30x+0.30y= 4.5    (iii)

Eliminate (ii) from (iii)

0.25y=1.2

y= 4.8   [divide both sides by 0.25]

put this in (i), we get

x+4.8=15

⇒ x= 15-4.8 = 10.2

Hence, Quantity of 30% NaOH = 10.2 L .

Quantity of 5% NaOH =4.8L .

answer:

total cost for tiles and paints is $924.  

step-by-step explanation:

we have been given that a community hall is in the shape of a cuboid. the hall is 40m long 15m high and 3m wide.

the paint will be required for 4 walls and ceiling.

let us find area of walls and ceiling.

therefore, the area of walls and ceiling is 1410 square meters.

given: cost for 10 litre of paint is $10 and 10 litre paint covers 25 square meter. therefore,

therefore, the total painting cost is $564.

tiles will be required for floor. let us find the area of floor.

given: 1m squared floor tiles costs $3. so,

therefore, the total tiles cost is $360.

now let us find combined total cost of tiles and paint.

therefore, the combined total cost of tiles and paint is $924.

answer: they are supplementary angles

step-by-step explanation: 161+19=180. supplementary angles equal 180 degrees