How many ml of 1: 4 solution and how many ml of sterile water are needed to prepare 600 ml of 1: 20 solution ?

Approximately 143 mL of 1:4 solution and 457 mL of water

Step-by-step explanation:

A 1:4 solution has a concentration of 1/(1+4) = 1/5 or 20%.

Similarly, a 1:20 solution has a concentration of 1/(1+20) = 1/21 or 4.76%.

If x is the mL of 20% solution and y is the mL of water, then:

x + y = 600

1/5 x = 1/21 (600)

Solve:

x = 5/21 (600)

x ≈ 143

y ≈ 457

You need approximately 143 mL of 1:4 solution and 457 mL of water.

Cost of 7 gallons=$24.50

Cost of 1 gallon=24.50/7=3.5

Cost of 15 gallons=15*3.5=52.5

Cost of 15 gallons will be $52.5

The answer is in the image 

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The answer is in the image 

y=2x+15

where y=Value of coin

x=Age in years

Value of coin after 19 years=2*19+15

=$53

Therefore, Value after 19 years=$53

The answer is in the image 

Salesperson will make 6% of 1800

=(6/100)*1800

=108

Salesperson will make $108 in $1800 sales

Area of rectangle= L*b

here,

L=12.4 cm

b= 8.8 cm

A= L*b

= 12.4 * 8.8 = 109.12 cm^2

Cost before sale tax=$46.00

Cost after including tax=$48.76

Sale tax=$48.76-46.00

=$2.76

we know,

sale tax=((sales tax rate)/100) * cost before sale tax

2.76=((sales tax rate)/100) *46.00

sale tax rate=(2.76*100)/46

                   =276/46

                    =6%

There fore sales tax rate=6%