Question

Difficulty: MediumRatios, Rates, and Proportions

A network router transmits data from two sources, Server AA and Server BB, at a constant ratio of 55 megabytes (MB\text{MB}) from Server AA for every 3 MB3\text{ MB} from Server BB. In a single session, the router transmitted a combined total of 160 MB160\text{ MB} of data from both servers. During the next session, the router transmits data at the same ratio, but the amount of data transmitted from Server AA is 20%20\% greater than the amount of data transmitted from Server AA in the first session. How many megabytes of data are transmitted from Server BB in the second session?

Answer: 72 MB

Answer

The amount of data transmitted from Server B in the second session is 72 megabytes.
To find the data transmitted from Server B in the second session, we first determine the individual data amounts from the first session. Given the ratio of data from Server A to Server B is 5:35:3 and the total is 160 MB160\text{ MB}, we can express their data amounts as 5x5x and 3x3x. Solving 5x+3x=1605x + 3x = 160 yields x=20x = 20. Thus, Server A transmitted 5×20=100 MB5 \times 20 = 100\text{ MB} and Server B transmitted 3×20=60 MB3 \times 20 = 60\text{ MB} in the first session. In the second session, the data from Server A increased by 20%20\%, yielding 100×1.20=120 MB100 \times 1.20 = 120\text{ MB}. Since the transmission ratio between Server A and Server B remains constant at 5:35:3, we can set up the proportion 120B=53\frac{120}{B} = \frac{5}{3}. Cross-multiplying gives 5B=3605B = 360, which solves to B=72B = 72 megabytes.

Step-by-Step Solution

1
Set up an equation for the total data in the first session.
5x+3x=160    8x=160    x=205x + 3x = 160 \implies 8x = 160 \implies x = 20
The ratio of data from Server A to Server B is 5:35:3, meaning the amounts can be represented as 5x5x and 3x3x for some multiplier xx.
2
Calculate the data transmitted from Server A in the first session.
A1=5(20)=100 MBA_1 = 5(20) = 100\text{ MB}
Multiply the ratio term for Server A by the scale factor xx to find its initial data contribution.
3
Calculate the increased data from Server A in the second session.
A2=100×(1+0.20)=120 MBA_2 = 100 \times (1 + 0.20) = 120\text{ MB}
Increase the first session's data from Server A by 20%20\%.
4
Use the constant ratio to find the data from Server B in the second session.
B2=72 MBB_2 = 72\text{ MB}
Set up the proportion 120B2=53\frac{120}{B_2} = \frac{5}{3} and solve for B2B_2 by cross-multiplying.

Key Concept

Solving part-to-part and part-to-whole ratio problems under proportional changes
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