If N is a prime number and 9N is less than 180 and greater than 81 then 13N -…
2024
If N is a prime number and 9N is less than 180 and greater than 81 then 13N - 7 is
- A.
107
- B.
162
- C.
123
- D.
156
Attempted by 2 students.
Show answer & explanation
Correct answer: B
Explanation:
Given:
N is a prime number.
9N is greater than 81 and less than 180.
This can be written as:
81 < 9N < 180
Divide the entire inequality by 9:
9 < N < 20
The prime numbers lying between 9 and 20 are:
11, 13, 17, and 19.
Now evaluate 13N − 7 for each possible value of N:
If N = 11, then 13N − 7 = 13 × 11 − 7 = 143 − 7 = 136.
If N = 13, then 13N − 7 = 13 × 13 − 7 = 169 − 7 = 162.
If N = 17, then 13N − 7 = 13 × 17 − 7 = 221 − 7 = 214.
If N = 19, then 13N − 7 = 13 × 19 − 7 = 247 − 7 = 240.
Among the given options, 162 is the only possible value.
Hence, the correct answer is 162.