The weather report

let,

A=number of days rained in day time

B=number of days it was clear in day time

C=number of days it rained in night time

D=number of days it was clear in night time

we have,

D=4 and B=5 and A+C=7

also A+B=x and C+D=x

A+B+C+D=x+x

(A+C)+B+D=2x

7+5+4=2x

2x=16

x=8

We figured that rainy night and day will be 4 and 3 respectivly, since sum is 7 and corresponding Night/Day sum will be same. Now we need to check if this fits to our condition - "all rainy night follows clear day".

• rainy nights = 4
• clear day = 5

So, we have sufficient days and table fulfill condition.

Total 8 days Sequence is as follows ( CN- Clear night, CD - Clear day, Rn - rainy night , Rd- rainy day) (RD,CN)(RD,CN)(RD,)(CD,CN)(CD,RN)(CD,RN)(CD,RN)(CD,RN)

let, A=number of days rained in day time B=number of days it was clear in day time C=number of days it rained in night time D=number of days it was clear in night time we have, D=4 and B=5 and A+C=7 also A+B=x and C+D=x A+B+C+D=x+x (A+C)+B+D=2x 7+5+4=2x 2x=16 x=8

I don't believe it is necessary to form a chart or create equations. One can see the answer simply by looking at the problem.

There were 7 rainy days and nights in all. There were 9 clear days and nights in all. Since the only possibilities given for the weather were "rainy" and "clear", there must be 16 days and nights in all.

16 days and nights = 8 (24-hour) days.

RD = rainy days; RN = rainly nights; X = total days

RN + RD = 7

X - RN = 4

X - RD = 5

combining first 2 equa:

X - 4 = 7 - RD

combining everything else:

X - 4 = 7 - (X - 5)

X = 8