Math Final Exam Review

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# Math Final Exam Review - PowerPoint PPT Presentation

Math Final Exam Review. Math for Water Technology MTH 082. Convert 188 o F to o C?. o C= 5 * ( o F – 32) 9 o C= 5 * (188-32)/9 o C= 87. 88 o F o C= 5 * ( o F – 32) 9 o C= 5 * (188-32)/9 o C= 87. Given Formula: Solve:. 31 O C 87 O C

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### Math Final Exam Review

Math for Water Technology

MTH 082

Convert 188oF to oC?

oC= 5 * (oF – 32)

9

oC= 5 * (188-32)/9

oC= 87

88 oF

oC= 5 * (oF – 32)

9

oC= 5 * (188-32)/9

oC= 87

• Given
• Formula:
• Solve:
• 31 OC
• 87 OC
• 122 OC
• 17 OC
A pipe is 16 inch in diameter and 550 ft long. How many gallons does the pipe contain?

DRAW:

• Given:
• Formula:
• Solve:
• 4295 gallons
• 5716 gallons
• 51670 gallons
• 7282 gallons

D= 16 in or 1.33 ft, L= 550 ft

V= 0.785(diameter2)(length)

V=(0.785)(1.33 ft)2(550 ft)

V= (0.785)(1.77ft2)(550 ft)

V= 764 ft3

V=(764ft3) (7.48 gal/1ft3)

V= 5716 gallons

D=16 in

l=550 ft

If a total of 10 ounces of dry polymer are added to 10 gallons of water, what is the percent strength (by weight) of the polymer solution?
• 93%
• 2%
• 0.05%
• 0.75%
• Given
• Formula
• Solve:

10 ounces of polymer (1lb/16 oz) =0.625 lbs

% Strength = Chem lbs * 100

(# gal)(Water lb) + Chem, Lbs

% Strength = 0.625 lbs *100

(10 gal) (8.34 lb/gal) + 0.625 lbs

% Strength = 0.625 lbs * 100%

84.03 lbs Sol

% Strength = 0.75%

If 25 lbs of a 10% strength solution are mixed with 50 lbs of a 1% solution, what is the percent strength of the new solution?
• 4 %
• 0.4 %
• 1 %
• 3 %

Solution #1= 20 lbs of 10% Solution #2 = 50 lbs of 1%

% Str of mix = Chem lbs in Sol #1 (% str/100) + Chem lbs in Sol#2 (% str/100) *100

Total lbs Sol #1 in Mix + Total lbs Sol #2 in Mix

% Str of mix = 25 lbs (10/100) + 50 lbs (1/100) *100

25 lbs Sol #1 + 50 lbs Sol #2 in Mix

% Str of mix = 3 lbs *100

75 lbs Sol

% Str of mix = 4 %

The flow from a faucet filled up a 1 gallon container in 52 seconds. What was the gpm flow rate from the faucet?
• 0.02 gpm
• 0.87 gpm
• 1.15 gpm
• 115 gpm

sec= 52 seconds = 52 sec/60sec/min=0.87 min

Flow, gpm= Volume (gal)

Time (min)

Flow, gpm = Vol (gal)

0.87 (min)

Flow, gpm = 1 (gal)

0.87 (min)

Flow, gpm= 1.15 gpm

Given

Formula

Solve:

If a pump discharges 10,350 g, in 3 hr and 45 minutes, how many gallons per minute is the pump discharging?

1. 36 gpm

2. 46 gpm

3. 3000 gpm

4. 155 gpm

#gal=?,Convert 3 hr=180 min+45 min=225 min

Rate=10,350 gallons

GPM(rate)= (gallons)/(minutes)

gpm= (10,350 g) = 46 gpm

(225 min)

How long (minutes) will it take to flush a 150 ft length of ¾ inch diameter service line if the flow through the line is 0.5 gpm?
• 3.4 min
• 6.34 min
• 12.68 min
• 111.8 min

D= ¾ inch (1ft/12 inch) =0.06 ft; L= 150 ft; Rate=0.5 gpm

A=0.785 (D)(D)(L)(7.48 gal/ft3)

Flow time, min= Pipe Volume (gal) (2)

Flow Rate, gpm

D= 0.75 in/12in/1ft=0.06 ft

Flow= 0.785 (0.06 ft)(0.06 ft)(150 ft)(7.48 gal/ft3)(2)

0.5 gpm

Flow = 12.68 min

Given

Formula

Solve:

A filter 20 ft by 25 ft receives a flow of 1940 gpm. What is the filtration rate in gpm/ft2?
• 3.9 gpd/ft3
• 3.9 gpm/ft2
• 0.25 gpm/ft2
• 0.25 gpd/ft3

Given

Formula

Solve:

L= 20 ft, W=25 ft; Rate 1940 gpm

A=L X W

Filtration Rate= (flow gpm)

Area (sq ft)

A= 20 ft X 25 ft = 500 ft2

Filtration Rate= (1940 gpm)

500 (sq ft)

Filtration Rate = 3.9 gpm/ft2

A water is tested and found to have a chlorine demand of 6 mg/L. The desired chlorine residual is 0.2 mg/L. How many lbs of chlorine will be required daily to chlorinate a flow of 8 mgd?

• Given
• Formula:
• Solve:
• 50 lb/d
• 400 lb/d
• 48 lb/d
• 414 lb/d

Demand= 6 mg/L, Residual = 0.2 mg/L, 8 mgd

Dose= Demand + Residual

Feed rate= (dosage)(flow rate)(conversion)

Dose = 6 mg/L + 0.2 mg/L

Dose= 6.2 mg/L

Feed rate= (dosage)(flow rate)(conversion)

FR= (6.2 mg/L)(8 mgd)(8.34 lbs/d)

FR= 414 lb/d

How many lbs of calcium hypochlorite (65% available chlorine) is required to disinfect a well if the casing is 18 inches in diameter and 220 ft long, with water level at 100 ft from the top of the well? The desired dose is 50 mg/L?

• 2 lbs
• 1 lbs
• .02 lbs
• 0.65 lbs

Given

Formula

Solve:

Cl= 65/100 D=18 in=1.5 ft Well 220-100 =120 ft

220 ft - 100 ft = 120 ft water in well

(0.785)(D2)(H) = ft3

(0.785)(1.5 ft)(1.5 ft) (120 ft)(7.48 gal/ft3)= 1585 gal

(50 mg/L)(.001585 MG)(8.34 lb/gal) = 1.01lbs

65/100

What is the motor horsepower (mph) for a pump with the following parameters? Motor Efficiency = 89% Total Head=144 ftPump Efficiency = 78% Flow=1.88 mgd

1. 0.0068 mph

2. 89 mph

3. 68 mph

4. 78 mph

GPM= (1.88mgd)(1,000,000gal/1M)(1day/1,440 min) = 1,306 gpm

89%=0.89 and 78% =0.78