Math Flashcards
What five steps would you use to solve the problem below:
In a classroom, the ratio of boys to girls is 4:3. If there are 28 boys, how many girls are there?
- Write as equation: 4:3 = 28:x
2: Write as fractions: 4/3 = 28/x
3: Cross multiply: 4x = 84
- Divide 4 on both sides to find x: x = 21
- Solution: 21 girls
What five steps would you use to solve the problem below:
The ratio of apples to oranges in a basket is 3:2. If there are 30 fruits in total, how many apples and how many oranges are there?
- Write as equation: 3x + 2x = 30
- Add x’s: 5x = 30
3: Divide 5 on both sides to find x: x = 6
- Multiply the value of x to the ratios: 3(6); 2(6)
- Solution: apples = 18; oranges = 12
What six steps would you use to solve the problem below:
The product of two whole numbers is 36, and their ratio is 1:4. What is the smaller number of the ratio?
- Write as equation: 1x * 4x = 36
- Multiply x’s: 4x^2 = 36
3: Find the square root: 2x = 6
- Divide 2 on both sides to find x: x = 3
- Multiply the value of x to the ratios: 1(3); 4(3)
- Solution: 3:12; smallest number is 3.
What two steps would you use to solve the problem below:
A meter was cut at the 35-cm mark. What is the ratio of the smaller piece to the larger piece?
- Find the length of the other half: If a meter is 100 cm, then 35:65
- Simplify the ratio by dividing by 5: Answer = 7:13
What five steps would you use to solve the problem below:
If ₽75.00 is shared among three children in the ratio of 3:7:15. The size of the smallest share is?
- Write equation: 3x + 7x + 15x = 75
- Add the x’s: 25x = 75
- Divide 25 on both sides to find x: x = 3
- Multiply the value of x to the ratios = 3(3):7(3):15(3)
- Solution: Smallest share is 9
How do you know if a number is divisible by 2?
If it ends in 0,2,4,6, or 8.
Even numbers are usually divisible by 2.
How do you know if a number is divisible by 3?
If the sum of all digits is divisible by 3.
How do you know if a number is divisible by 4?
If the last two digits are divisible by 4
How do you know if a number is divisible by 5?
If the number ends in 0 or 5
How do you know if a number is divisible by 6?
If it is divisible by 2 and 3
How do you know if a number is divisible by 7?
- You multiply the last digit of the number by 2.
Ex: 252 = 2*2 = 4
- You subtract the result to the remaining digits.
Ex: 25-4 = 21
- If the end result is divisible by 7, then it is divisible by 7.
Ex: 21/7 = 3
How do you know if a number is divisible by 8?
If the number formed by the last 3 digits is divisible by 8.
If a number ends in 000, is it divisible by 8?
Yes.
How do you know if a number is divisible by 9?
If the sum of all digits is divisible by 9.
How do you know if a number is divisible by 11?
Three steps:
- Add all the numbers in the odd places.
- Add all the numbers in the even places.
- Subtract the results from Steps 1 and 2.
If the difference is divisible by 11, then it is divisible by 11.
How do you know if a number is divisible by 12?
If the number is divisible by both 3 and 4.
How do you add two numbers with different signs?
You subtract their base values then adopt the sign of the bigger number.
-8 + (+4) = -4
Why does the result adopt a negative sign?
Because the bigger number (8) uses a negative sign.
8 + (-4) = 4
Why does the result adopt a positive sign?
Because the bigger number (8) uses a positive sign.
When we simplify equation from -12 - (-7), to -12 + 7
Why does 7 eventually turn into a positive sign?
Because negative signs beside each other cancel each other out and turn positive.
How do you find the area of a square?
side^2
How do you find the area of a rectangle?
length * width
How do you find the area of a right triangle?
ab/2
How do you find the hypotenuse of a right triangle?
c^2 = a^2 + b^2
How do you find the area of a circle?
Pi(r^2)
How do you find the area of a parallelogram?
b*h
How do you find the area of a trapezoid?
[(a+b)*h]/2
What is the formula for simple interest (SI)?
(PRT)/100
P (Principal amount)
R (Rate of interest)
T (Time period, years)
What is the formula for future value?
F = P + SI
What is being asked in the problem below?
Vanille invested P5,000 in a certain business. How much will his money be in 2 years if it earns 12% interest in a year?
Future Value
What is another term for Future Value?
Total Amount
Rate of interest, when multiplying to the Principal Amount and Time, should be in decimal form.
True or False?
False. It should be taken as base value.
Ex: If R = 12%, it should be computed as 12 not .12
Time period, when multiplying to the Principal Amount and Rate of interest, is always in years.
True or False?
True. If a given time period is in months, just divide it by 12.
Ex: 3 months (3/12 = 1/4 = .25 years)
How do you convert a mixed fraction to an improper fraction?
For ex: 2 3/5 is?
Multiply the denominator to the whole number and add the product to the numerator.
2 3/5 = 13/5
Convert .111111111 to a fraction
1/9
(a+b)+c = a+(b+c) is what property?
Associative Property of Addition
(ab)c = a(bc) is what property?
Associative Property of Multiplication
a(b+c) is what property?
Distributive Property
a+b = b+a is what property?
Commutative Property of Addition
ab = ba is what property?
Commutative Property of Multiplication
If given a set of scores, what formula do you use to find the RANGE?
Biggest Number - Smallest Number
The equation of a line with equal coordinates is?
y = x
A = 3x + 2y + 6xy is?
12 (no one knows why though)
A = 3x + 2y is?
12 (no one knows why though)
What is the formula of a slope?
Rise (X) over Run (Y)
If a line is purely horizontal (aka only y), what is the value of its slope?
0
If a line is purely vertical (aka only x), what is the value of its slope?
Undefined
How many seconds are there in a 24 hour day?
86,400 seconds
Given the algebraic term: 4xy
What is the numerical coefficient and what is the literal coefficient?
NC = 4
LC = xy
What’s the different between Prime and Composite Numbers?
Prime numbers are numbers with only two factors: 1 and itself.
Composite numbers are natural numbers with factors more than 1 and itself.
What are the formulas for discount rate and discounted price respectively
DR = Discount over original price
DP = Original price - Selling price
Convert the following whole numbers into fractions: 2, 4, 6
4/2
16/4
36/6
How do you find the perimeter of a shape?
Add all the sides BITCH!!!!
What’s the difference between complementary and supplementary angles?
Complementary angles are two angles that add up to 90 degrees, while supplementary angles are two angles that add up to 180 degrees.
What is the slope-intercept form?
line = slope + y-intercept
y = mx + b
What formula do you use to find the interior angle of a polygon?
180*(number of sides - 2) all divided by number of sides
What is the passing percentage if 83,152 examinees passed out of 228,963 in the LET?
36.32% (just memorize it)
If a math problem in the LET, asks for a Toyota and Kia car, and these are the variables:
70 km, 2 hrs, 5 hrs
What answer should u remember?
50 kmph