The following graph shows the percent change in revenue for a manufact

Question

The following graph shows the percent change in revenue for a manufacturing company from the years 1988 to 1994. 
  https://gmatclub.com/forum/download/file.php?mode=view&id=60684  
 On the basis of the graph, please answer the questions that follow.

3. From 1988 to 1994, how many years was the revenue greater than it was in 1987?  GRAPH_1_PLACEHOLDER

4. Please choose this drop-down as a Graphs question needs to have 2  GRAPH_2_PLACEHOLDER .

The First two questions based on this stem can be found here.

SR4896 · Accepted Answer

Assume revenue in 1987 as 100.
Revenue for subsequent years shall be 130,97.5, 126.75,101.4,86.19,103.428, 93.0852.
Thus, for 4 times, revenue is greater than 100

pshreyan_17 · Answer

Hi, 
Is there any quick way to solve this question?
Or do we need to calculate revenue for every year taking the reference point in 1987?

Shwetabh54 · Answer

I have solved this question by 3 methods.

1. Letting the 1987 value be 1000
2. Letting the 1987 value be x 
3. By applying successive percentage concept.

It was easy with letting the value x

PFB the solution :-

Let 1987 value was x

1988 =   1.3x  
1989 = 1.3x * 0.75 = 0.975 x which is approx. 0.97x (to simplify further calculations)
1990 = 0.97x * 1.3 = 1.261 x which is approx.   1.3x  
1991 = 1.3x * 0.8 =   1.04x   
1992 = 1.04x * 0.85 = 0.884x ~ 0.9x
1993 = 0.9x * 1.2 = 1.08x ~  1.1x  
1994 = 1.1x * 0.9 = 0.99x

Now you can observe that bold & underline 4 values are greater than x and rest are less than x. Hence 4 values are greater than x.

egmat · Answer

You DO need to track the cumulative effect, but there's an efficient way to do it.

When dealing with percent change graphs and comparing to a base year, you must account for the cumulative effect of all changes.

Efficient Approach:  
 Step 1:  Set  1987 = 100  (as your base)
 Step 2:  Apply each year's percent change sequentially
 Step 3:  Any result  > 100  means revenue exceeded  1987

Example: 
-  1987:100  (base)
-  1988:  If graph shows  +20%  →  100 × 1.20 = 120  ✓ (above  1987 )
-  1989:  If graph shows  -30%  →  120 × 0.70 = 84  ✗ (below  1987 )
-  1990:  If graph shows  +25%  →  84 × 1.25 = 105  ✓ (above  1987 )

Time-saving tip:  You don't need exact calculations - just track whether you're above or below  100 .

Common mistake:   Adding/subtracting percentages directly (e.g., thinking  +20% - 30% = -10%  overall). This ignores the compounding effect!

Therefore , while there's no way to completely avoid tracking each year, using  100  as your base makes the mental math much faster.

The following graph shows the percent change in revenue for a manufact

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The following graph shows the percent change in revenue for a manufact

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