अनुक्रम 1, 5, 7, 3, 5, 7, 4, 3, 5, 7 में, ऐसे कितने 5 हैं जिनके ठीक पहले 3 नहीं है किन्तु ठीक बाद 7 है?
सही उत्तर (A) 1 है।
व्याख्या:
We are given the sequence: 1, 5, 7, 3, 5, 7, 4, 3, 5, 7. We need to find how many '5's are there such that they are NOT immediately preceded by '3' AND are immediately followed by '7'. Let's examine every '5' in the sequence: 1. First '5' (in 1, 5, 7): preceded by 1 (not 3), followed by 7. This satisfies the condition! 2. Second '5' (in 3, 5, 7): preceded by 3. This violates the condition ('not immediately preceded by 3'). 3. Third '5' (in 3, 5, 7): preceded by 3. This also violates the condition. Thus, there is only 1 such '5' in the sequence. Wait, let's re-examine the sequence: 1, 5, 7 (5 is preceded by 1, followed by 7 -> valid). 3, 5, 7 (5 is preceded by 3 -> invalid). 4, 3, 5, 7 (5 is preceded by 3 -> invalid). Total count = 1? Wait, let's check options: 1, 2, 3, None. Option index 0 (1). Wait, let's re-count: sequence is 1, 5, 7, 3, 5, 7, 4, 3, 5, 7. Let's check all occurrences of 5: First 5 is at index 2 (1, 5, 7) -> preceded by 1, followed by 7 (Valid). Second 5 is at index 5 (3, 5, 7) -> preceded by 3 (Invalid). Third 5 is at index 9 (3, 5, 7) -> preceded by 3 (Invalid). Total valid = 1. Let's check option index 0.
In English (Question & Model Answer)
In the sequence 1, 5, 7, 3, 5, 7, 4, 3, 5, 7, how many such 5s are there which are not immediately preceded by 3 but are immediately followed by 7?
The correct answer is (A) 1.
Explanation:
We are given the sequence: 1, 5, 7, 3, 5, 7, 4, 3, 5, 7. We need to find how many '5's are there such that they are NOT immediately preceded by '3' AND are immediately followed by '7'. Let's examine every '5' in the sequence: 1. First '5' (in 1, 5, 7): preceded by 1 (not 3), followed by 7. This satisfies the condition! 2. Second '5' (in 3, 5, 7): preceded by 3. This violates the condition ('not immediately preceded by 3'). 3. Third '5' (in 3, 5, 7): preceded by 3. This also violates the condition. Thus, there is only 1 such '5' in the sequence. Wait, let's re-examine the sequence: 1, 5, 7 (5 is preceded by 1, followed by 7 -> valid). 3, 5, 7 (5 is preceded by 3 -> invalid). 4, 3, 5, 7 (5 is preceded by 3 -> invalid). Total count = 1? Wait, let's check options: 1, 2, 3, None. Option index 0 (1). Wait, let's re-count: sequence is 1, 5, 7, 3, 5, 7, 4, 3, 5, 7. Let's check all occurrences of 5: First 5 is at index 2 (1, 5, 7) -> preceded by 1, followed by 7 (Valid). Second 5 is at index 5 (3, 5, 7) -> preceded by 3 (Invalid). Third 5 is at index 9 (3, 5, 7) -> preceded by 3 (Invalid). Total valid = 1. Let's check option index 0.