F.1的數學題－貨運百科

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F.1的數學題

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Question: A local mobile phone company provides the following 2 SMS plans:Plan A: $88 (including first 450 SMS per month); for each extra SMS: $0.2Plan B: $20 (including first 70 SMS per month); for each extra SMS: $0.3 a) it is known that Franki and Stephen are using plan A and plan B respectively, and... 顯示更多 Question: A local mobile phone company provides the following 2 SMS plans: Plan A: $88 (including first 450 SMS per month); for each extra SMS: $0.2 Plan B: $20 (including first 70 SMS per month); for each extra SMS: $0.3 a) it is known that Franki and Stephen are using plan A and plan B respectively, and the number of SMS sent by each of them last month exceeds the corresponding limit. Let x and y be the number of SMS sent by Frankin and Stephen last month respectively. Find: if Frankin and Stephen sent 465 and 308 SMS last month respectively, how much would be the fee payable by each of them last month? B) Starting from this month, sending SMS among customers of this mobile phone company is free of charge, and this will not be counted as SMS included in the service plan. this month, Frankin and Stephen sent the same number of SMS to each other, and the total number of SMS sent by each of them is the same as that in the last month, and thus their fees payable for this month are the same as last ,onth. How many SMS did they send to each other this month? End of question. I can only work out the ans for part a, and part b is too confusing.

最佳解答:

Qa) Given that the number of SMS sent by each exceeds the corresponding limit. Stepten sent 308 SMS, so he is using Plan B. Fee payable: = $20 + ( 308-70 ) x 0.3 = $20 + 71.4 = $91.4 Franki sent 465 SMS, so he is using Plan A. Fee payable: = $88 + ( 465-450 ) x 0.2 = $88 + 3 = $91 Qb) Let S be the number of SMS that they send to each other this month. 20 + ( 308-70-S ) x 0.3 = 88 + ( 465-450-S ) x 0.2 20 + 71.4 - 0.3S = 88 + 3 - 0.2S 0.1S = 0.4 S = 4 Therefore, they send 4 SMS to each other in this month.

其他解答:5AEEC82B53E1B405