Estimation and Rounding
Positive,Negative and PEMDAS
Rates and Ratios
Fractions Decimals and Percents
More Rates and Ratios
100
What is 4.356 rounded to the nearest tenths?
4.4 (Look at the digit in the tenths place, and the digit right after it will tell you if you need to round up or stay where you are. Remember, if the next digit is less than 5, stay where you are!))
100
-8 x -6 + -4 =
44 (Remember, a negative x negative = positive, but a positive x negative = negative.)
100
Simplify this ratio: 25: 125: 75.
1:5:3 (Find tha greatest common factor, GCF, of the numbers and divide by that to simplify.)
100
What is 0.375 in fraction form?
3 eighths (3/8) (Remember, 1/8 is half of 1/4, so if 1/4 is 0.25, then 1/8 must be 0.125.)
100
Simplify the ratio: 40cm : 2.8m
1cm : 7cm (First convert everything into the same unit of measure, ex., 40cm: 280cm. Then divide by the GCF.)
200
Round 0.00981 to the nearest thousandths.
0.010 (In this case, the 9 is in the thousandths place, but the 8 next to it says "round up". SO the 9 becomes a 10. You need the 0 in the thousandths place to have a correct answer.)
200
4 + -5 x -6 - 10 =
24 (Do -5 x -6 first. Then the problem becomes 4 + 30 - 10)
200
Three people share €27,000 in the ratio 1:2:6. How much does each person get?
€3,000 €6,000 and €18,000 (There are 9 total parts, 1:2:6, and 1 part is the total €27,000 divided by 9, so €3,000.)
200
Which would you rather have: €4,500 or 12% of €42,000?
12% of 42,000 (12% of 42,00 is 0.12 x 42,000 = €5040)
200
What is 10km/hr converted into m/s? (meters per second)
10,000m/3600s = 2.78m/s (10km = 10,000m, 1hr = 3600s)
300
Estimate the answer. A mouse's heart beats 650 times a minute. How many times does it beat in 59 minutes?
Various answers are acceptable here. 42,000 times a minute or 39,000 times. (650 rounds to 700. 59 minutes round to 60 minutes. 700 x 60 = 42,000. You could also leave 650 and just round the 59 to get 650x 60 = 39,000.)
300
5^2 - 6 + 2^3 x 4 =
51 5^2 = 25 2^3 =8 25 - 6 + 8 x 4 = 25 - 6 + 32 = 51
300
Red, Blue and Green marbles in a jar have the ratio 2:5:8. If there are 225 marbles in the jar, how many are green?
120 green marbles (Add the ratios 2:5:8 = 15 parts. If there are 225 marbles, each part is 225/15 or 15 marbles. Since green has 8 parts, 8 x 15 = 120 marbles.)
300
One person scores 45 out of 48 points, and another scores 55 out of 58 points? Who had the better percentage? What are their percentages?
93.75% vs. 94.8%, The person who scored 55 out of 58 had the better score. (45/48 = 93.75% 55/58 = 94.8%)
300
One Singapore dollar equals 5.2 Swedish krona. A shirt at H&M in Sweden costs 400 kronor, and the same shirts costs 79SDG in Singapore. Where can you buy the cheaper shirt?
Buy in Sweden. (Convert everything to the same currency. 400kr = 400/5.2 = 76.9SGD 79SDG = 79 x 5.2 = 410.8 kronor.)
400
Estimate the answer. A person gets 147 out of 210 problems right on a test. (killer test.) About what percentage did they receive on the test?
75% (147 is rounded to 150, 210 goes to 200, and 150 out of 200 is 3/4 or 75%.)
400
0.12 x 10 + 4.4 - 3.2 x 2 / 2 =
2.4 0.12 x 10 = 1.2 2/2 = 1 1.2 + 4.4 - 3.2 = 2.4
400
If I run 1.7 m/s, how long does it take me to run a marathon? (42.2 kilometers)
About 7 hours 1.7m/s = 6120 m/hr (1.7 x 3600) 6120 m/hr = 6.12 km/hr (6120 /1000) 42.2 km / 6.12km = 6.9 hrs
400
The runner up on the Biggest Loser lost 100 lbs and started at 245 lbs. What is the minimum amount of weight the winner had to have lost if her starting weight was 289 lbs? (The winner loses a higher percentage of body weight.)
119lbs. Th runner-up lost 59.2% (145/245) 59.2% of 289 = 171 lbs. 289 - 171 = 118lbs, so the winner needs to lose more than this, so 119 lbs.
400
Gold coins in a pouch each weigh 150grams and silver coins weight 80g. There are 25 coins in the pouch, and the pouch weighs 2.7kg. How many gold and silver coins are in the pouch?
10 gold coins and 15 silver coins. Try a Guess and check method if you have a hard time using ratios.
500
About what fraction is this decimal: 0.131131131..... (never ending)
13/100 0.131131... is about 0.131 which is 131/1000. 130/1000 = 13/100
500
What does PEMDAS stand for?
P= Parenthesis E = Exponent M = Multiply D = Divide A = Add S = Subtract
500
City A and City B are 1100km apart. Lee leaves City A at 8:00AM and travels 100km/hr. Jack leaves City B at 9:30AM and travels 150km/hr. What time do they meet?
1:36PM Draw a picture and make a table hour for hour then, minute for minute.
500
23% of the student body is in the 8th grade. There are 80 eight-graders. How many students are there total?
348 students (80 / 0.23 = 347.9 or 348)
500
On a map with scale 1:50,000, San Francisco and Pal Alto are 88.9cm apart. How far apart are they in real life?
44.45km 1:50,000 means 1cm on the map is 50,000cm in real life. 88.9cm on the map is 4,445,000cm in real life, which is 44,450meters, or 44.45 km.
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