Exercise: Basic Operations
Questions for: Simplification & BODMAS
Evaluate: 4/5 ÷ 2/3 of (15/8 - 1/4) + (2.5 + 1.5) × 3 - 7
A: 373/65
B: 139/20
C: 199/35
D: 48/65
Answer: A
The expression is: 4/5 ÷ 2/3 of (15/8 - 1/4) + (2.5 + 1.5) × 3 - 7
Step 1: Solve the operations inside the parentheses (Brackets).
(15/8 - 1/4) = (15/8 - 2/8) = 13/8
(2.5 + 1.5) = 4
The expression becomes: 4/5 ÷ 2/3 of 13/8 + 4 × 3 - 7
Step 2: Solve the 'of' operation.
2/3 of 13/8 = (2/3) × (13/8) = 26/24 = 13/12
The expression becomes: 4/5 ÷ 13/12 + 4 × 3 - 7
Step 3: Solve Division and Multiplication from left to right.
Division: 4/5 ÷ 13/12 = 4/5 × 12/13 = 48/65
Multiplication: 4 × 3 = 12
The expression becomes: 48/65 + 12 - 7
Step 4: Solve Addition and Subtraction from left to right.
48/65 + 12 - 7 = 48/65 + 5
To add a fraction and an integer, convert the integer to a fraction with the same denominator:
5 = 5 × 65 / 65 = 325/65
48/65 + 325/65 = (48 + 325)/65 = 373/65
Why others are wrong:
A — Correct answer.
B — This results from incorrectly performing division before the 'of' operation.
C — This results from an error in calculating the first bracket, specifically in the fraction subtraction.
D — This results from omitting the final addition of '5' to the fraction 48/65.
Simplify the following mathematical expression using the correct order of operations:
Evaluate: `24 ÷ [ (3/4 of 16) - 2.5 × (12 ÷ 6) ] + (5/8 - 1/4)`
A: `213/56`
B: `192/59`
C: `171/56`
D: `55/14`
Answer: A
1. Resolve `(3/4 of 16)`: `(3/4) × 16 = 12`.
2. Resolve `(12 ÷ 6)`: `2`.
3. Substitute these values back: `24 ÷ [ 12 - 2.5 × 2 ] + (5/8 - 1/4)`.
4. Resolve `2.5 × 2` inside the brackets: `5`.
5. Substitute back: `24 ÷ [ 12 - 5 ] + (5/8 - 1/4)`.
6. Resolve `12 - 5` inside the brackets: `7`.
7. Resolve `(5/8 - 1/4)`: `(5/8 - 2/8) = 3/8`.
8. Substitute back: `24 ÷ 7 + 3/8`.
9. Perform the division: `24/7`.
10. Perform the addition: `24/7 + 3/8`.
11. Find a common denominator (56): `(24 × 8) / (7 × 8) + (3 × 7) / (8 × 7)`.
12. Calculate: `192/56 + 21/56`.
13. Sum the fractions: `(192 + 21) / 56 = 213/56`.
Why others are wrong:
B — Incorrectly performed the final division after adding `7 + 3/8`.
C — Incorrectly performed subtraction instead of addition in the final step (`24/7 - 3/8`).
D — Made an error in the fraction subtraction `(5/8 - 1/4)`, potentially simplifying to `1/2` incorrectly.
Discuss About this Question.
Evaluate the following expression:
[ 45 ÷ 3 × (7 + 2 of 5) - 3^2 ] + 18 ÷ 6
A: 249
B: 669
C: 252
D: 44
Answer: A
The expression is [ 45 ÷ 3 × (7 + 2 of 5) - 3^2 ] + 18 ÷ 6
Step 1: Solve the operation 'of' inside the innermost parenthesis. (2 of 5 = 2 × 5 = 10)
Expression becomes: [ 45 ÷ 3 × (7 + 10) - 3^2 ] + 18 ÷ 6
Step 2: Solve the addition inside the innermost parenthesis. (7 + 10 = 17)
Expression becomes: [ 45 ÷ 3 × 17 - 3^2 ] + 18 ÷ 6
Step 3: Solve the exponent. (3^2 = 9)
Expression becomes: [ 45 ÷ 3 × 17 - 9 ] + 18 ÷ 6
Step 4: Perform division and multiplication from left to right inside the main bracket. (45 ÷ 3 = 15)
Expression becomes: [ 15 × 17 - 9 ] + 18 ÷ 6
Step 5: Perform multiplication inside the main bracket. (15 × 17 = 255)
Expression becomes: [ 255 - 9 ] + 18 ÷ 6
Step 6: Perform subtraction inside the main bracket. (255 - 9 = 246)
Expression becomes: 246 + 18 ÷ 6
Step 7: Perform division outside the bracket. (18 ÷ 6 = 3)
Expression becomes: 246 + 3
Step 8: Perform the final addition. (246 + 3 = 249)
The final answer is 249.
Why others are wrong:
B — Incorrectly performed addition before 'of' multiplication within the parentheses, treating `(7 + 2 of 5)` as `(7 + 2) × 5`.
C — Incorrectly calculated the exponent `3^2` as `3 × 2` (resulting in 6 instead of 9).
D — Incorrectly performed addition before division for the final operations outside the bracket.
Discuss About this Question.
Evaluate: `[ (0.5 ÷ 1/8) + (3/5 of 50) ] × 2/17 - 1`
A: 2.54
B: -30
C: 5.42
D: 5
Answer: A
The order of operations (BODMAS/PEMDAS) must be followed: Brackets, Orders (powers/roots, 'of'), Division/Multiplication (left to right), Addition/Subtraction (left to right).
1. **Solve operations inside the inner parentheses:**
* `(0.5 ÷ 1/8)`: Convert 0.5 to a fraction (1/2).
* (1/2 ÷ 1/8) = (1/2 × 8/1) = 8/2 = 4
* `(3/5 of 50)`: 'of' means multiplication.
* (3/5 × 50) = (3 × 50) / 5 = 150 / 5 = 30
2. **Substitute these values back into the main bracket and solve:**
* `[ 4 + 30 ] = 34`
3. **Perform multiplication outside the bracket:**
* `34 × 2/17`
* (34 × 2) / 17 = 68 / 17 = 4
4. **Perform the final subtraction:**
* `4 - 1 = 3`
Wait, I made a mistake in identifying the correct answer in my thought process. The correct answer should be `3`.
Let me re-check the distractors and reassign the correct answer letter.
Correct answer: [A/B/C/D] should be E if I had 5 options. Let's make 3 one of the options.
My options were:
A. 2.54
B. -30
C. 5.42
D. 5
My correct calculation is 3.
I need to make `3` one of the options.
Let's make Option D the correct answer: 3. And move `5` to A or C.
New Options:
A. 2.54
B. -30
C. 5.42
D. 3
Correct answer: D
Explanation (why this):
The order of operations (BODMAS/PEMDAS) must be followed: Brackets, Orders (powers/roots, 'of'), Division/Multiplication (left to right), Addition/Subtraction (left to right).
1. **Solve operations inside the inner parentheses:**
* `(0.5 ÷ 1/8)`: Convert 0.5 to a fraction (1/2).
* (1/2 ÷ 1/8) = (1/2 × 8/1) = 8/2 = 4
* `(3/5 of 50)`: 'of' means multiplication.
* (3/5 × 50) = (3 × 50) / 5 = 150 / 5 = 30
2. **Substitute these values back into the main bracket and solve:**
* `[ 4 + 30 ] = 34`
3. **Perform multiplication outside the bracket:**
* `34 × 2/17`
* (34 × 2) / 17 = 68 / 17 = 4
4. **Perform the final subtraction:**
* `4 - 1 = 3`
Why others are wrong:
A — Incorrectly calculated `0.5 ÷ 1/8` as `0.5 × 1/8`.
B — Performed subtraction `(2/17 - 1)` before multiplication `(34 × 2/17)`.
C — Misinterpreted 'of' operation `(3/5 of 50)` as addition `(3/5 + 50)`.
This looks good now.
The output should be plain text, so I'll write it out exactly.
---
One last check for the question statement. "Evaluate" is standard. The numbers are medium-difficult. No cultural specifics.
The `Why the others are wrong` section lists a specific reason for A, B, C.
For D (the correct answer), no reason is needed there.
Final re-check. Looks compliant.
Evaluate: `[ (0.5 ÷ 1/8) + (3/5 of 50) ] × 2/17 - 1`
A. 2.54
B. -30
C. 5.42
D. 3
Correct answer: D
Explanation (why this):
1. **Solve operations inside the inner parentheses first (BODMAS/PEMDAS - Brackets):**
* `(0.5 ÷ 1/8)`: Convert 0.5 to a fraction (1/2).
* (1/2 ÷ 1/8) = (1/2 × 8/1) = 8/2 = 4
* `(3/5 of 50)`: The word 'of' indicates multiplication (BODMAS/PEMDAS - Orders).
* (3/5 × 50) = (3 × 50) / 5 = 150 / 5 = 30
2. **Substitute these values back into the main bracket and solve (BODMAS/PEMDAS - Brackets):**
* `[ 4 + 30 ] = 34`
3. **Perform multiplication outside the bracket (BODMAS/PEMDAS - Multiplication):**
* `34 × 2/17` = (34 × 2) / 17 = 68 / 17 = 4
4. **Perform the final subtraction (BODMAS/PEMDAS - Subtraction):**
* `4 - 1 = 3`
Why the others are wrong:
A — This result would occur if `0.5 ÷ 1/8` was incorrectly calculated as `0.5 × 1/8`.
B — This result would occur if the subtraction `(2/17 - 1)` was performed before the multiplication `(34 × 2/17)`.
C — This result would occur if the 'of' operation in `(3/5 of 50)` was misinterpreted as addition `(3/5 + 50)`.
Discuss About this Question.
Evaluate: [3/4 + (5/6 of 18/5 - 1/2) ÷ 7/8] × 2/3
A: 101/42
B: 311/126
C: 52/21
D: 85/42
Answer: A
1. Solve the expression inside the innermost parenthesis: (5/6 of 18/5 - 1/2)
* First, perform 'of' (multiplication): 5/6 × 18/5 = (5 × 18) / (6 × 5) = 18/6 = 3.
* Now, perform subtraction: 3 - 1/2 = 6/2 - 1/2 = 5/2.
* The expression becomes: [3/4 + (5/2) ÷ 7/8] × 2/3.
2. Next, solve the division within the square bracket: (5/2) ÷ 7/8.
* (5/2) ÷ 7/8 = 5/2 × 8/7 = (5 × 8) / (2 × 7) = 40/14 = 20/7.
* The expression becomes: [3/4 + 20/7] × 2/3.
3. Perform the addition within the square bracket: 3/4 + 20/7.
* Find a common denominator, which is 28.
* 3/4 = (3 × 7) / (4 × 7) = 21/28.
* 20/7 = (20 × 4) / (7 × 4) = 80/28.
* 21/28 + 80/28 = 101/28.
* The expression becomes: 101/28 × 2/3.
4. Finally, perform the multiplication: 101/28 × 2/3.
* (101 × 2) / (28 × 3) = 202 / 84.
* Simplify the fraction by dividing both numerator and denominator by 2: 101/42.
Why others are wrong:
B — This result is obtained if division is performed before 'of' within the innermost parenthesis, i.e., (18/5 - 1/2) is calculated first, then 5/6 is multiplied by the result.
C — This result occurs if addition (3/4 + 5/2) is performed before division (5/2 ÷ 7/8) within the main square bracket.
D — This result is obtained if a calculation error is made, specifically if 3 - 1/2 is incorrectly taken as 2 instead of 5/2.
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