Rajesh applies once every year for a ticket to a music festival. The probability that he is successful in any particular year is 0.3, independently of other years.
- (a)Find the probability that Rajesh is successful for the first time on his 7th attempt.[1]
- (b)Find the probability that Rajesh is successful for the first time before his 6th attempt.[2]
- (c)Find the probability that Rajesh is successful for the second time on his 10th attempt.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.
- [B1] 352947/10000000 or 0.03529... to at least 3sf.
- [M1] 1-0.7ᵈ, d = 5, 6.
- [A1] Accept 0.83193 to at least 3sf. If M0 scored, SC B1 for 0.8319[3].
- [(M1)] 0.3+(0.3)(0.7)+(0.3)(0.7)² + (0.3)(0.7)³ +(0.3)(0.7)⁴[+(0.3)(0.7)⁵]
- [(A1)] Accept 0.83193 to at least 3sf. If M0 scored, SC B1 for 0.8319[3].
- [M1] (0.7)⁸ × (0.3)² x k, k a positive integer, 1 may be implied. No addition/subtraction/additional terms.
- [A1]
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