৫টি সংখ্যার সমষ্টি ১০০ যার প্রথম ৩টি সংখ্যার গড় ২০ এবং শেষ তিনটি সংখ্যার গড় ১৫ হলে, তৃতীয় সংখ্যাটি কত?
A
৫
B
১০
C
১৫
D
১২
উত্তরের বিবরণ
প্রশ্ন: ৫টি সংখ্যার সমষ্টি ১০০ যার প্রথম ৩টি সংখ্যার গড় ২০ এবং শেষ তিনটি সংখ্যার গড় ১৫ হলে, তৃতীয় সংখ্যাটি কত?
সমাধান:
ধরি,
সংখ্যাগুলো যথাক্রমে a, b, c, d, e
∴ a + b + c + d + e = ১০০
a + b + c = (২০ × ৩) = ৬০
এবং, c + d + e = (১৫ × ৩) = ৪৫
∴ (a + b + c) + (c + d + e) - (a + b + c + d + e) = ৬০ + ৪৫ - ১০০
∴ c = ৫
অর্থাৎ তৃতীয় সংখ্যাটি = ৫
0
Updated: 20 hours ago
2, 8 এবং
32 এর জ্যামিতিক গড় কত?
Created: 3 weeks ago
A
9.33
B
9
C
8
D
7
সমাধানঃ
আমরা জানি,
n সংখ্যক সংখ্যার গুণোত্তর গড় বা জ্যামিতিক গড় 
∴ 2, 8 এবং 32 এর জ্যামিতিক গড় = (2 × 8 × 32)1/3
= (512)1/3
= (83)1/3
= 8
0
Updated: 3 weeks ago
There are 71 members in group A, 18 members in group B and 53 members in group C. All the members of these groups went to a restaurant. The average amount spent on each member of group A, B and C is Tk.397, Tk.421 and Tk.137 respectively. The total average amount (in Tk.) spent per member is-
Created: 3 weeks ago
A
Tk. 295
B
Tk. 335
C
Tk. 402
D
Tk. 303
Question: There are 71 members in group A, 18 members in group B and 53 members in group C. All the members of these groups went to a restaurant. The average amount spent on each member of group A, B and C is Tk.397, Tk.421 and Tk.137 respectively. The total average amount (in Tk.) spent per member is-
Solution:
Given that,
Members in A = 71, B = 18, C = 53
Average spent per member: A = Tk. 397, B = Tk. 421 and C = Tk. 137
Now,
Total amount by A = 71 × 397 = 28187
Total amount by B = 18 × 421 = 7578
Total amount by C = 53 × 137 = 7261
∴ Total amount = 28187 + 7578 + 7261 = 43026
∴ Total members = 71 + 18 + 53 = 142
∴ Average = 43026/142 = 303
Total average amount spent per member = Tk. 303
0
Updated: 3 weeks ago
Average age of 15 students of a class is 15 years. Out of these the average age of 5 students is 14 years and that of the other 9 students is 16 years. The age of the 15th student is-
Created: 3 weeks ago
A
15 years
B
11 years
C
9 years
D
18 years
Question: Average age of 15 students of a class is 15 years. Out of these the average age of 5 students is 14 years and that of the other 9 students is 16 years. The age of the 15th student is-
Solution:
Given that
Average age of 15 students = 15 years
Average age of 5 students = 14 years
Average age of 9 students = 16 years
Now,
Total age of all 15 students = 15 × 15 = 225 years
Total age of 5 students = 5 × 14 = 70 years
Total age of 9 students = 9 × 16 = 144 years
∴ Age of the 15th student = 225 - (70 + 144) = 225 - 214 = 11 years
0
Updated: 3 weeks ago
