The average speed would be 600 km/hr.
Step-by-step explanation:
Let the original speed be 'x'
Let the decreased speed be 'x-200'
Distance = 600 km
Time increased by 30 minutes
According to question, it becomes,

So, The average speed would be 600 km/hr.
Answer:
X = {8n – 7n – 1 : n ϵ N}
Y = {49 (n –1) : n ϵ N} — (1) [all terms divisible by 49]
X = {8n – 7n – 1}
= (1 + 7)n – 7n – 1
= 1 + nC1 7 + nC2 72 + ….. + nCn 7n – 7n – 1
= nC2 72 + …… + nCn 7n
= 49 [nC2 + nC3 7 + …. nCn 7n-2] — (2)
From (1) and (2),
X is divisible by 49.
Y has all multiples of 49.
X ⊂ Y
Answer:
11
Step-by-step explanation: