Answers:
1. 1 Hr and 30 min is same as that of 90 minutes
2. I think its 1/1,2/2,.....9/9(check with Shakuntala devi puzzles book)
3. 32 * 2 =68(since every tangent provides 2 point of intersection on the circle boundaries)
4.Check shakuntala devi book
5. 14(8 + 9 +.......+71) sice 14 * 8 =112(above 100 and multiple of 14) and 14*71 =994(below 1000)
Now
use sum of n no.s formula i.e. n(n+1)
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= 14( from sum of 1 to 71 subtractthe sum of 1 to 7,since we need the sum from 8 to 71 which is a multiple of 14)
=14 [71(72) - 7(8)]
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22
= 14 [ 2556 - 28 ]
=14*2528
=35392(check the values,but I think this method will work out)