What is the surface area of a solid sphere with radius 7 cm?
A ) 100πcm²
B ) 194 πcm²
C ) 196πcm² ✅
D ) 198πcm²
Surface Area of Sphere = 4πr²
For r = 7:
7² = 49
49 ÷ 7 = 7
4 × 22 × 7 = 616 OR 196πcm²
Answer = 616 cm²
FORMULAS
1.Surface Area of Sphere = 4πr²
2.Volume of Sphere = (4/3)πr³
EXAM TIP
Whenever the radius is a multiple of 7, use:
π = 22/7
If three consecutive integers have sum 54 what is the smallest one?
A ) 17 ✅
B ) 18
C ) 21
D ) 22
RULE
Three consecutive integers:
• Middle number = Sum ÷ 3
• Smallest number = (Sum ÷ 3) − 1
• Largest number = (Sum ÷ 3) + 1
Example:
Sum = 54
Middle = 54 ÷ 3 = 18
Smallest = 18 − 1 = 17
Largest = 18 + 1 = 19
Answer = 17